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OPS335 Lab 4b

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→‎INVESTIGATION 1: INSTALL THUNDERBIRD (MUA) and SETUP A REFERENCE CLIENT
[[Category:OPS335]][[Category:OPS335 Labs]] = Email Servers =OVERVIEW=={{Admon/important|Warning|Your lab 4a must be complete before you can start this lab.}} In Lab 4a, you configured and ran the '''Postfix''' application for our MTA (a.k.a. SMTP server) on your '''vm2''' and '''vm3''' machines.
You may not That setup has some major drawbacks::* It required an SMTP server ('''MTA''') to be configured on each machine.:* The Message Store ('''MS''') would also be aware of it as unique to each machine - what a user but email is a very complex system to administer, in fact it's a very complex system of received on one server would not exist on any other archaic, hard-to-configure, sometimes-interoperable complex systems.
We're going to spend three weeks working on it In this lab you will centralize some of this information, so that by the end of the course you will have a general understanding of what services are involved user can send email from any machine in sending, filteringthe network, and reading email. You will also have the skills incoming mail sent to configure a basic setup using the default services on CentOS 7centralized messages store.
== Overview =='''The a diagram below (duplicate to lab 4a) shows your basic setup of your email system:'''
This is a simple (yeah, really) diagram of how you can send an email to someone else:
[[Image:Email-servers.png]]
You will begin by modifying the existing '''Postfix''' ('''MTA''') servers to make mail they send come from your domain (instead of each machine). Then you will add a record to your DNS server to allow mail to be sent to the domain itself, instead of the individual machines. Next, you will add a Local Delivery Agent ('''LDA''') to your '''vm3''' by installing '''dovecot-lda''', configure it, and test it to make sure that is is working correctly. Finally, you will set up an '''IMAP''' server called '''Dovecot''' on your '''vm3''' machine, so you can read your email from an MUA such as ''Thunderbird'' or a ''Webmail'' application. You will set up a webmail application called '''Roundcube''' in a later lab). === Learning About the Services Involved in an Email Delivery === In reality, the terms '''MTA''', '''MDA''', '''MUA''', '''LDA''' can actually be considered misleading since some of those services can be combined together to form a single entity (application), while other applications may operate as separate entities. There may be overlap, so if you don't find those acronyms helpful, don't worry too much about them. On the other hand, when referred to in diagrams, they can help to visualize those processes when trying to understand how an e-mail system works. [http://wiki.dovecot.org/MailServerOverview Here is an overview] of those terms (from the Dovecot wiki). It is worth viewing this link. In the diagram displayed above, the elements include: * '''User Account'''. The individual who wants to send or receive mail messages.* '''MUA''' (email client). This is the application that the individual uses to send or receive mail messages. It can be a '''native application''' or a '''web application'''. You will learn how to setup and use both types of these applications throughout the remainder of this course.* Two '''MTA''' servers. These are the servers responsible for getting your emails to the <u>destination</u> server.** They are similar to routers (which route packets) but work on the <u>application</u> layer rather than the <u>network</u> layer.** In our example, there are only two MTAs - but there can be several.** You connect to your MTA over a <u>secure</u> connection, so your emails can't be read by the operators of the network you're connected to.** The mail message then travels the rest of the way to the destination MTA <u>unencrypted</u>, so anyone with access to the routers in-between can read all your emails. That is why many organizations will refuse to send you confidential information over email.* '''LDA/MDA''' Server. This server will receive the email from the MTA, and will store it on disk in some format. '''MailDir''' and '''MBOX''' are the most popular mailbox formats.* '''IMAP/POP3''' server(s). When sending an email, you send it to the destination using your MTA, but you also want to save it in your '''"Sent"''' folder for yourself. This is accomplished by a separate connection to either your '''IMAP''' or '''POP3''' server.** Thus, a situation can occur that although you sent your email successfully, it may never make it to your "Sent" folder - the <u>second</u> connection to your IMAP server is quite unrelated to the first connection to the '''SMTP''' server.* '''DNS''' Server. A DNS server is also involved - it is needed to retrieve the address of the email server responsible for email for a particular domain. This is done with '''MX''' records. ===Online References=== * [Categoryhttps:OPS335//help.ubuntu.com/community/Dovecot Dovecot Community Documentation]* [http://wiki.dovecot.org/LDA Dovecot-lda]* [[Categoryhttp:OPS335 Labs]//wiki.dovecot.org/LDA/Postfix Configuring dovecot-lda with postfix] == INVESTIGATION 1: INSTALL THUNDERBIRD (MUA) and SETUP A REFERENCE CLIENT== Unlike the '''mailx''' (MUA) application you installed and used in Lab 4a, this lab will be using the '''Thunderbird''' (MUA) application instead which is a graphical application that uses a '''centralized Message Store''' (MS) to retrieve and read mail messages.  Although we will be eventually setting up the Thunderbird application to perform all the mail operations discussed above, you need to learn to '''"walk before you can run"'''. Eventually, you are going to set up all those mail services, but to begin with, you will set up an email client to connect to an already working server which is the '''Seneca email server'''. Once we learn how to do this for our Seneca email account, then we can use it for our mail servers for our VM2 and VM3. '''Perform the following steps:''' #Switch to your '''host''' machine, and install the '''Thunderbird''' email application.#When you first launch the Thunderbird application, a configuration dialog should appear as shown in the diagram below:
The diagram above doesn't even include reading <br>::[[Image:Seneca-student-thunderbird-email, but it's as simple as it gets (if you want to run an email server)-setup. You will need to learn to administer basics of all png|600px]]<br><ol><li value="3">Use the systems data in the diagram. We won't go in too much depth, only table below to configure the minimum you need. But we will not (Thunderbird settings dialog box for example) go over every detail of Postfix, which on its own has a rather [httpsYOUR Seneca e-mail account:</li></en.wikipedia.org/wiki/Postfix_%28software%29#Architecture complex] [https://www.credativ.de/blog/postfix-architecture-overview diagram].ol>
{| class="wikitable" border="1" style= Services involved in "margin-left:40px;"! Setting !! '''Incoming: IMAP''' !! '''Outgoing: SMTP'''|-| '''Username'''|| yoursenecauserid@myseneca.ca || yoursenecauserid@myseneca.ca|-| '''servername''' || outlook.office365.com || outlook.office365.com|-| '''port''' || 993 || 587|-| '''security''' || SSL/TLS || STARTTLS|-| '''References''' | colspan="2" | [1] [https://employees.senecacollege.ca/spaces/77/it-services/wiki/view/2394/other-email delivery ===-clients ITS - Configuring other Email Clients]|}
The terms MTA, MDA, MUA, LDA are not 100% well defined, because few of the related services are simple and do exactly one thing. There ::Note that your username is overlap, so if you don't find the acronyms helpful - don't worry about themyour full email address(<em>yourid@myseneca. But they can help organize your thoughts when trying to keep all this in your headca</em>) and not just <em>yourid</em>.
[http://wiki.dovecot.org/MailServerOverview Here's an overview] of from the Dovecot wiki, it's worth reading.
{{Admon/important |Unencrypted Options|Notice that there are <u>unencrypted</u> options available to connect to your SMTP/IMAP servers but those are rarely used these days - the potential for abuse is too great. On a free wifi network, the operator would be able to not only read your email, but also obtain your password without any password/encryption cracking tools. In our diagram we havefact, even on a private wired network, it is not uncommon for an employer to use a packet sniffer utility to monitor all the traffic going over their network (Packet Sniffing applications were actually found to be legally acceptable practice if used by the management of organizations)}}<br><ol><li value="3">After you create your '''Thunderbird''' account, you should be able to read your existing email and send new email within the Thunderbird application.</li><li>Take time to view your ''Account Settings'' and ''Preferences'' to get a feel for what settings exist. For example:<ul><li>How often will Thunderbird check for new messages?</li><li>Will the messages you write be in HTML or plain text?</li><li>How do you change your SMTP server settings? Why are they in a different section?</li></ul></li><li>The main objective of this section was to learn how to setup your Thunderbird application to read your Seneca email, so in the next section you can use the exact type of setup for your own email server.</li></ol>
* A user. That's the person who wants to send an email.* An MUA (email client). This is the application the user uses to send an email. It can be a native application or a web application. We'll set up both types.* Two MTAs. These are the servers responsible for getting your emails to the destination server.** They are similar to routers (whcih route packets) but work on the application layer rather than the network layer.** In our example there are only two MTAs - but there can be several.** You connect to your MTA over a secure connection, so your emails can't be read by the operators of the network you're connected to.** The rest of the way to the destination MTA the emails travel completely unencryptedRecord steps, so anyone with access to the routers in between can read all your emails. This is why many organizations will refuse to send you confidential information over email.* The LDA/MDA will receive the email from the MTAcommands, and will store it on disk your observations in some format. MailDir and MBOX are the most popular mailbox formats.* When sending an email you send it to the destination using your MTA, but you also want to save it INVESTIGATION 1 in your "Sent" folder for yourself. This is accomplished by a separate connection to your IMAP or POP3 server.** This is why it can happen that you sent your email successfully but it never makes it to your "Sent" folder OPS335 lab log- the second connection to your IMAP server is quite unrelated to the first connection to the SMTP server.* Note that a DNS server is also involved - itbook'''s needed to retrieve the address of the email server responsible for email for a particular domain. This is done with the MX records we looked at in the DNS labs.
== Reference client setup INVESTIGATION 2: SETUP A CENTRALIZED MESSAGE STORE ==
Eventually we're going === Setup Your MTA to set up all those services, but to begin with we'll set up an email client to connect to a (hopefully) working server - the Seneca email server. This will be a good exercise with an email client.Use Correct Domain===
Install Thunderbird on In Lab 4a, both of your hostemail servers were sending mail messages addressed from users of the actual machines themselves. This would be confusing for the receiver who might get emails from the same user @vm1, vm2, and configure it like vm3. Which would they respond to? To avoid thisproblem from occurring, obviously using your own information:we can make all servers make the sent mail appear to come from a central location (usually the '''domain'''), and make incoming email sent to that address to be accessible from machines within our network.
[[Image'''Perform the following steps:Seneca-student-thunderbird-email-setup.png|600px]]'''
Notice that there are unencrypted options available to connect # Issue the '''mail''' command to view the email messages you sent between your '''vm2''' and '''vm3''' in your SMTP/IMAP servers but those are rarely used these dayslab 4a. The potential for abuse Notice that each is too greataddressed from root on whichever machine sent it. # On a free wifi network both machines (vm2 and vm3), edit the operator would be able to not only read your email - but also get your password, without any password'''/etc/postfix/encryption cracking toolsmain. And even on a private network - it is not uncommon for an employer cf''' file to change the '''myorigin''' parameter from '''$myhostname''' to sniff all '''$mydomain'''. Restart the traffic going over their network '''postfix''' service.# Now, send emails messages (via the '''mail''' command) between both of your vm2 and vm3 machines, and view the mail messages by issuing '''mail''' in each vm. The sender address should now read that was found in court to be a legally acceptable practice)the received mail messages came from '''root@yourdomain.ops'''.
The specific security settings depend on how your servers were configured. The settings for the seneca servers are [https://inside.senecacollege.ca/its/services/email/email_clients/imap.html published here].
After you create your account - you should be able ::The next step is to read your existing configure what addresses that the server will receive email for. This is done using postfix by setting the '''mydestination''' parameter (configuration variable) to include '''$mydomain''' (this is assuming you've set up '''mydomain''', '''myorigin''' , and send new email in Thunderbird'''inet_interfaces''' properly).
Look through the Account Settings and Preferences to get a feel for what settings exist. For example:
* How often will Thunderbird check for new messages?
* Will the messages you write be in HTML or plain text?
* How do you change your SMTP server settings? Why are they in a different section?
If everything is working - that<ol><li value="4">Edit the '''/etc/postfix/main.cf''' file for '''vm3 ONLY'''s good, now you know what youscroll down to the line containing: 'll try ''mydestination''' and change line to build in the email labstext shown below:<br><source>mydestination = $mydomain, $myhostname, localhost. The goal $mydomain, localhost</source>'''Note:''' Even though your machine's name is ''vm3.yoursenecaid.ops'', your postfix MTA will also receive emails addressed to have the exact same setup using your servers instead domain called: yoursenecaid.ops</li></ol><br>::In order for this to work, we need to add a DNS record that will point mail sent to the domain towards one of Seneca the SMTP serversconfigured to accept it.
<ol><li value= MTA for sending (no encryption) ="5">Add an '''MX''' record to the forward lookup zone on '''host''' so that all incoming mail addressed to the domain is sent to your vm3.</li><li>Restart the service and use the '''dig''' command to confirm that it works.</li><li>Send an email from your '''vm2''' to '''root@yourdomain.ops'''</li><li>Confirm that it arrives on your '''vm3''' machine</li></ol>
We'll use Postfix as the MTA, and we'll set it up on '''vm2'''. This will be the email server for your internal network. You'll be able to send email out of your network, and receive email from within your network, but not receive from outside your network because:# Outsiders will never find the MX recors for your domain, because there are no .org servers pointing to your DNS server (you haven't paid for it).# Even if they did - your local network is using IP addresses on a private subnet, which is not routeable on the internet, so it cannot be reached from the outside.=== Relay Email Through Another Server===
Postfix should be installed by default. If When email is sent from either vm, it isnis addressed from the domain, but receiving MTAs might query why mail sent from vm2 doesn't match the address of the MX record for the domain. This would be a red- go ahead and install itflag for potential spam. Install also the netstat application To avoid this, we can relay all mail sent from vm2 (use yum search or any other machine in our network) through vm3 so that it properly appears to find come from the package name) and mail server that matches the MX record for the telnet commanddomain.
Postfix will work with the default configuration, so enable it, start it, and check that it's running. Also look for it in ''Perform the list of listening portsfollowing steps:'''
# Move to your vm2 machine.# Direct your '''vm2''' MTA to relay mail through vm3, by making the following editing change for the '''/etc/postfix/main.cf''' file:<br><source lang>relayhost ="bash"vm3.<yourdomain>netstat -atnp.ops</source># Restart the '''postfix''' service.# Next, you must instruct your '''vm3''' machine to allow your vm2 machine to pass email through it by making the following editing change to the '''/etc/postfix/main.cf''' file:<br><source>mynetworks = 192.168.X.0/24</source>NOTE: Substitute in your '''own network''' for X<br><br># Restart the '''postfix''' service.
Which one All mail is it? Find the port used by SMTP, now being delivered to a centralized location (and look for connctions with the state LISTEN (i.e. currently listeningalso appears to be coming from that same location), but a user would still have to access that server to retrieve it.
== Testing = Install and Configure the connection to Postfix Local Delivery Agent (LDA/MDA) ===
Connect from your Postfix is capable of performing the function of an LDA, but its LDA capabilities are limited, thus postfix is generally not used for that purpose. Currently, the most popular LDA is ''LMTP'', but we will be installing, configuring, and using an LDA called '''Dovecot''' since it is also popular and we will setting up Dovecot as an '''IMAP''' server to your later in this lab. Using both Postfix and Dovecot will actually increase the performance of our IMAP server using telnet:.
<source lang="bash">telnet localhost 25</source>'''Perform the following steps:'''
Note that it will tell you once #Move to your connect that '''Escape character vm3''' machine.#Dovecot is not installed when you installed your Virtual machines in previous labs.<br>Install the Dovecot application by issuing the following command:<br><source>yum install dovecot</source>#Edit your '^]''/etc/postfix/main.cf', which means your can hold control '' file and press the square bracket key scroll down to end the session (and then exit the telnet appor search for)'''mailbox_command'''.Add the following line:<br><source>mailbox_command = /usr/libexec/dovecot/dovecot-lda -f "$SENDER" -a "$RECIPIENT"</source>
::NOTE: Do <u>'''not'''</u> replace any variables, those are set automatically by Postfix when it runs the LDA. If this worked you are interested in learning more about the Dovecot application, you can read about dovecot- that means lda [http://wiki.dovecot.org/LDA/Postfix here] and [http://wiki.dovecot.org/LDA here].<br><ol><li value="4">Finally, edit the '''/etc/dovecot/conf.d/10-mail.conf''' file and indicate where you want your mail delivered by including the following line:<source>mail_location = maildir:~/Maildir</source></li><li>Restart your postfix service is running and listening and responding to connections. Let's see if it works from </li><li>While the emails are still stored only on VM3, they will now be easier for other machines/services to access. Telnet </li><li>Due to vm2 from permissions on the host (connect to directories where mail will now be stored, root will no longer receive mail. Check the SMTP port) and see if it works. If your firewall is set up properly - it shouldn't, you'll need to allow incomming connections logs for an indication as to TCP port 25why.</li></ol>
Once you open the port '''Record steps, commands, and your observations in the firewall INVESTIGATION 2 in your OPS335 lab log- try the telnet command. You should get a different error this time. This time the problem is that your service isnbook''t listening on the outside interface, it's currently configured to listen only on the loopback (lo) interface.
== Listen on all interfaces INVESTIGATION 3: USING THUNDERBIRD (MUA) FOR VM2 and VM3 MACHINES ==
The first change to the Postfix configuration will be to make it listen for incoming connections === Accessing Received Mail Messages on the extrnal intercace, that's eth0 from the VMs point of view.VM3 VIA IMAP ===
First, we will set up the IMAP server so we can read email. The configuration file is '''/etc/postfix/maincurrent way we have configured our mail server on our VM3 machine should allow all the email for anyaccount@yoursenecaid.cfops should be delivered to our ''' Edit it and change '''inet_interfacesvm3''' machine. We will set up Dovecot with IMAP to get easy access to '''all'''that email.
At this point we should also set the string that will end up in the '''FromPerform the following steps:''' header in messages sent by this server. Change '''mydomain''' to your domain name and and '''myorigin''' to '''$mydomain'''.
Restart postfix, confirm #The configuration file for the Dovecot service (with netstatwhich is not the same thing as dovecot-lda) is: '''/etc/dovecot/dovecot.conf'''. Modify the '''protocols''' option so that Dovecot will work with IMAP connections, no POP3 or LMTP.# Start the dovecot service, and ensure itwill always start automatically when the machine boots.# Use the 's now ''ss''' command to confirm the service is listening , and use '''nc''' on the '''host''' to confirm you can connect to it.# You'll probably fail, so using the information gathered from '''ss''', modify the firewall on all interfacesvm3 to allow IMAP connections from your local network and try '''nc''' again. Once it works, do not just loopbackforget to save this change so it will still be there the next time you reboot.#If you can connect - it's now time to do something wrong, that is allow connections to our IMAP server over an unencrypted connection.# Edit the '''/etc/dovecot/conf.d/10-auth.conf''' file and test connecting set '''disable_plaintext_auth''' to it from '''no'''.# Then edit the '''/etc/dovecot/conf.d/10-ssl.conf''' file and set '''ssl''' to '''yes'''.<br><br>'''Note:''' This combination of parameters will allow your username and password to be sent over the internet in plain text, for anyone interested to look at. In a later lab we'll set up secure SMTP and IMAP connections, for now this is all we have time for.<br><br># Restart dovecot so the hostchanges take effect.
== Setup = Connecting to IMAP Servers Using Thunderbird ===
We are far from having a working email server but at this point we have enough to be able to test it with Thunderbird.'''Perform the following steps:'''
The process is a little challenging because Thunderbird tries really hard #On your '''host''' machine, return to prevent you from connecting to a server that doesn't work the Mail Account Setup dialog box (and ours mostly doesn't work at this pointeg. near top of lab). # Set it up a '''new email account'''. You will be using account settings to connect to your IP address (192.168.X.3) '''vm2''' for '''SMTP''' and '''vm3''' for both '''IMAP and SMTP'''. Use <u>no </u> encryption, and use normal password authentication for IMAP (we don't have an IMAP server running yet, but that's ok).Refer to the diagram below for reference:
[[Image:ops335-email-step1.png|600px]]
<ol><li value="3">Try to connect to your IMAP server with Thunderbird wonby clicking on your ''t let 'Inbox'''.</li><li>If nothing happens, then check the Thunderbird Activity Manager for any errors. If the connection is successful, you should see the '''Trash''' box <u>appear</u> below Inbox.</li><li>Use the Thunderbird application to send an email to your myseneca address. If you proceed with 've done everything right, it will send the message successfully</li><li>Verify that your message has been sent. Check your myseneca email and look at '''/var/log/maillog''' on vm2 (your email server).</li></ol> === Sending a Mail Message from VM2 (Using Thunderbird)=== '''Perform the following steps:''' #Use the "Done" button because '''ss''' and '''nc''' commands (like you did in lab 4a) to confirm your service is listening on the correct ports/interfaces. You will fail probably have to connect open the appropriate firewall port on '''vm3''' to allow incoming '''SMTP''' connections.<br><br>'''Note:''' You should be able to send email to any regular user <u>on</u> '''vm3''' using the email address '''yourusername@yoursenecaid.ops''' using the Thunderbird application on your host machine (which is configured to IMAPuse the account on your vm2).<br><br> <ol><li value="2">Create a new account on your '''vm3''' machine using only your <u>first</u> name. We will use this account as a one-time "test" if the mail message has been received on your VM3 machine (from your VM2 machine). Use <br><br>'''Note:''' It is <u>'''important'''</u> that you '''<u>don't</u>''' create this same account name on your vm2 machine, since you want to easily identify the difference between the sending and receiving SMTP servers.<br /><br /></li></ol> <ol><li value="Advanced config3" button >Use the new account in Thunderbird to send an email to '''firstname@yoursenecaid.ops''' and then check the contents of '''/home/firstname/Maildir/new/''' on your '''vm3''' machine. There should be a file there with the contents of your email.</li><li>If there is no file, then check the log file '''/var/log/maillog''' to see what went wrong.</li><li>If you can see a file in the '''/home/firstname/Maildir/new/''' directory, then review the procedures on how you got the email server working (since you have performed many steps and set up many services).</li><li>Refer to bypass the diagram at the top of this lab. Which services have you currently set up? Record your findings in your lab Logbook.</li></ol> {{Admon/important |Encountering error messages when sending email|If you cannot properly receive sent e-mail messages, check the '''/var/log/syslog''' file for errors.<br><br> If you locate an error message in that checkfile such as: '''Fatal: Error reading configuration: Invalid settings...''', then add the following <u>parameter</u> in '''/etc/dovecot/dovecot.conf''':<br />'''postmaster_address <nowiki>=</nowiki> DOMAIN''' (where DOMAIN is actually <u>your</u> domain).<br /><br />After you have saved those changes, then '''restart''' your dovecot service. This problem can also be resolved by properly setting the hostname of your machine to include the domain.}}
There is only one configuration parameter {{Admon/important |Backup your VMs!|You MUST perform a '''full backup''' of ALL of your VMs whenever you complete your '''OPS335 labs''' or when working on your '''OPS335 assignments'''. You should be using the dump or rsync command, and you should use the Bash shell script that needs you were adviced to be changed create in Thunderbird to get it to send an email order to backup all of your myseneca email. Try to send an email from the new account - it will give you an error messageVMs.}}
After you fix the configuration '''Record steps, commands, and your observations in INVESTIGATION 3 in your OPS335 lab log- try again. This time it will send the message successfully but it will fail to save it in the Sent folder, because thatbook''s done with IMAP and you don't have an IMAP server yet.
Still - verify that your message has been sent. Check your myseneca email and look at '''/var/log/maillog''' on vm2 (your email server).== COMPLETING THE LAB ==
= Completing ==Online Submission===Follow the Lab instructions for lab 4b on blackboard.<!--===Andrew's sections===
Students should be prepared with You may choose to:* Submit screenshots of your work on Blackboard, in which case you don'''all required commands (system information) displayed in a terminal (or multiple terminals) prior t need to come to the lab.* Or come to calling the instructor for signoff''lab, show me your work, and talk to me about it. I want to hear what you've learned and answer any questions you have.
You'''Arrange evidence (command output) for each ll get the same grade regardless of these items on how you choose to submit your screen, then ask your instructor to review them and sign off on the lab's completion:'''work.
::<span style="color:green;font-size:1.5em;">&#x2713;</span>Status and configuration of your Postfix service on vm2.
::<span style="color:green;font-size:1.5em;">&#x2713;</span>Your Thunderbird configuration.
::<span style="color:green;font-size:1.5em;">&#x2713;</span>The email you sent to your myseneca account.
::<span style="color:green;font-size:1.5em;">&#x2713;</span>Download and run '''wget https://ict.senecacollege.ca/~andrew.smith/ops335/labcheck4b.bash''' on your '''c7host''' machine.
::<span style="color:green;font-size:1.5em;">&#x2713;</span>Completed Lab4b log-book notes.
-->
 
==EXPLORATION QUESTIONS==
 
# What is the purpose of the Thunderbird application?
# List the steps to configure your DNS to allow your Thunderbird application to connect to your mail server.
# What is the purpose of the '''Dovecot''' package?
# What is the purpose of the '''mydestination''' parameter contained in the '''/etc/postfix/main.cf''' file?
# Why are '''IMAP''' and '''POP''' email servers placed on separate machines (vms)?
# What is the purpose of the '''mail_location''' parameter contained in the '''/etc/dovecot/conf.d/10-mail.conf''' file?
# Why is root not able to receive mail with the changed mail location? What could you change to allow mail to be sent to root again?
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