Differences

This shows you the differences between two versions of the page.

--- computing:mailserver [2022/12/11 03:56] – oemb1905
+++ computing:mailserver [2025/04/23 20:55] (current) – oemb1905
@@ Line 2: / Line 2: @@
   * **mailserver**
   * **Jonathan Haack**
   * **Haack's Networking**
   * **webmaster@haacksnetworking.org**
 -------------------------------------------
 //mailserver//
 -------------------------------------------
-This tutorial is for users of Debian GNU/Linux who want to set up a proper email server.. This tutorial assumes you know how to set up A, AAAA, SPF, DKIM, DMARC, MX, and PTR records. Set an A record for example.org and mail.example.org. If you don't know how, then learn up, and do not proceed. //Thanks to LinuxBabe for a great jumping off point//.
+This tutorial is for users of Debian GNU/Linux who want to set up a proper email server.. This tutorial assumes you know how to set up A, AAAA, SPF, DKIM, DMARC, MX, and PTR records. Set an A record for example.org and mail.example.org. If you don't know how, then learn up, and do not proceed. //Thanks to LinuxBabe for a great jumping off point//. Let's begin by editing our hosts file ''sudo nano /etc/hosts'' as follows:
-  sudo nano /etc/hosts
-Edit the second line and add a line to the bottom similar to:
-  <127.0.1.1 example.org example>
-  <127.0.0.1 mail.example.org localhost>
-Install postfix and mailutils
+.0.1.1 example.org example
+.0.0.1 mail.example.org localhost
-  sudo apt-get install mailutils postfix -y
+Install postfix and mailutils ''sudo apt-get install mailutils postfix -y'' picking ''Internet Site'' and set your domain to ''example.org''.
-  <Internet Site>
-  <example.org>
 Install firewall, open common ports for front facing website, and for imap/smtp:
@@ Line 30: / Line 22: @@
   sudo apt install ufw
   sudo ufw allow 22/tcp
-  sudo ufw allow 53/tcp
   sudo ufw allow 25/tcp
   sudo ufw allow 587/tcp
   sudo ufw allow 143/tcp
+  sudo ufw allow 465/tcp
   sudo ufw allow 993/tcp
   sudo ufw allow 80
@@ Line 42: / Line 34: @@
   sudo postconf -e message_size_limit=52428800
-Set hostname and aliases
+Set hostname and aliases in ''sudo nano /etc/postfix/main.cf'' and make sure that the hostname, origin, destination, mailbox size, and quota are set. Also, in my case, I only have ipv4 support, so I explicitly set that as well.
-  sudo nano /etc/postfix/main.cf
-Make sure that the hostname, origin, destination, mailbox size, and quota are set. Also, in my case, I only have ipv4 support, so I explicitly sett that as well.
   myhostname = mail.example.com
@@ Line 62: / Line 50: @@
 Now, set up the server block for your mail server's website:
-  sudo nano /etc/apache2/sites-available/mail.example.com.conf
+  sudo nano /etc/nginx/conf.d/mail.example.com.conf
   sudo mkdir -p /usr/share/nginx/html/
@@ Line 121: / Line 109: @@
   smtp_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
-Now, we can install dovecot and configure it to use IMAP, change the default mailbox location, and add dovecot to the mail group:
+Now, let's configure and enable SASL support. Open ''/etc/postfix/main.cf'' and enter:
+  # SASL Authentication with Dovecot
+  smtpd_sasl_auth_enable = yes
+  smtpd_sasl_type = dovecot
+  smtpd_sasl_path = private/auth
+  smtpd_sasl_security_options = noanonymous
+Now, we can install dovecot and configure it to use IMAP and lmtp. Install the packages with ''sudo apt install dovecot-core dovecot-imapd dovecot-lmtpd'' and then edit ''sudo nano /etc/dovecot/dovecot.conf'':
+  <protocols = imap lmtp>
+After that, open ''sudo nano /etc/dovecot/conf.d/10-mail.conf'' and change the default mail director location as follows:
-  sudo apt install dovecot-core dovecot-imapd
-  sudo nano /etc/dovecot/dovecot.conf
-  <protocols = imap>
-  sudo nano /etc/dovecot/conf.d/10-mail.conf
   <mail_location = maildir:~/Maildir>
+Let's make sure dovecot is part of the mail group, including any users you intend to use email:
   sudo adduser dovecot mail
+  sudo adduser username mail
-sdsd
+Now we can configure dovecot over at ''sudo nano /etc/dovecot/conf.d/10-master.conf'' in order to be able to leverage lmtp:
-Note that when upgrading postfix, please select "No configuration" as otherwise it will overwrite out configurations.
+  service lmtp {
+    unix_listener /var/spool/postfix/private/dovecot-lmtp {
+     mode = 0600
+     user = postfix
+     group = postfix
+    }
+   }
+Similarly, we need to edit postfix for lmtp as well with ''sudo nano /etc/postfix/main.cf'' and then specifying:
+  mailbox_transport = lmtp:unix:private/dovecot-lmtp
+  smtputf8_enable = no
+Next, let's configure dovecot authorization with ''sudo nano /etc/dovecot/conf.d/10-auth.conf'' plain login as follows:
+  disable_plaintext_auth = yes
+  auth_username_format = %n
+  auth_mechanisms = plain login
+Now, configure SSL/TLS encryption in dovecot using your website/domain certs from earlier with ''sudo nano /etc/dovecot/conf.d/10-ssl.conf'':
+  ssl = required
+  ssl_cert = </etc/letsencrypt/live/mail.example.com/fullchain.pem
+  ssl_key = </etc/letsencrypt/live/mail.example.com/privkey.pem
+  ssl_prefer_server_ciphers = yes
+  ssl_min_protocol = TLSv1.2
+Set up the SASL listener by editing ''sudo nano /etc/dovecot/conf.d/10-master.conf'' and adding this block:
+  service auth {
+    unix_listener /var/spool/postfix/private/auth {
+      mode = 0660
+      user = postfix
+      group = postfix
+    }
+  }
+If you have errors or can't connect your email client at this point, you can test your handshakes as follows:
+  openssl s_client -connect mail.example.com:465
+  openssl s_client -starttls smtp -connect mail.example.com:25
+Now it is time to setup an spf policy agent so that the incoming email that is received checks for validity of spf records. **Do not confuse this with creating an spf TXT record for your outgoing email.** Let's install spf policy with ''sudo apt install postfix-policyd-spf-python''and then edit ''sudo nano /etc/postfix/master.cf'' as follows:
+  policyd-spf  unix  -       n       n       -       0       spawn
+  user=policyd-spf argv=/usr/bin/policyd-spf
+After that, let's set up ''sudo nano /etc/postfix/main.cf'' as follows:
+  policyd-spf_time_limit = 3600
+  smtpd_recipient_restrictions =
+   permit_mynetworks,
+   permit_sasl_authenticated,
+   reject_unauth_destination,
+   check_policy_service unix:private/policyd-spf
+Now, it is time to set up DKIM on your server. After creating the DKIM record/key on your server, you will need to create a corresponding TXT record for it to establish that anything over smtp with that signature is, in fact, you/your server. Let's install opendkim with ''sudo apt install opendkim opendkim-tools'' and add postfix to its group with ''sudo adduser postfix opendkim'' and then adjust the configuration in ''sudo nano /etc/opendkim.conf'' as follows:
+  Canonicalization   relaxed/simple
+  Mode               sv
+  SubDomains         no
+  Nameservers     8.8.8.8,1.1.1.1
+  KeyTable           refile:/etc/opendkim/key.table
+  SigningTable       refile:/etc/opendkim/signing.table
+  ExternalIgnoreList  /etc/opendkim/trusted.hosts
+  InternalHosts       /etc/opendkim/trusted.hosts
+Now that the configuration for DKIM is ready, let's create the keys and content for the locations specified above:
+  sudo mkdir -p /etc/opendkim/keys
+  sudo chown -R opendkim:opendkim /etc/opendkim
+  sudo chmod 711 /etc/opendkim/keys
+Once all the directories and key locations are created, let's open the signing table with ''sudo nano /etc/opendkim/signing.table'' and enter the following (without the single quotes required here due to markdown conflict):
+  '*@example.com      default._domainkey.example.com'
+  '*@*.example.com    default._domainkey.example.com'
+Now that the signing table is setup, we need to edit the key table with ''sudo nano /etc/opendkim/key.table'' and enter the following:
+  default._domainkey.example.com     example.com:default:/etc/opendkim/keys/example.com/default.private
+The trusted hosts is next, over in ''sudo nano /etc/opendkim/trusted.hosts'' which we simply enter:
+.0.0.1
+  localhost
+  .domain.com
+We now need to cut the DKIM keys (and make sure to add TXT records on your DNS host later) as follows:
+  sudo mkdir /etc/opendkim/keys/example.com
+  sudo opendkim-genkey -b 2048 -d example.com -D /etc/opendkim/keys/example.com -s default -v
+  sudo chown opendkim:opendkim /etc/opendkim/keys/example.com/default.private
+  sudo chmod 600 /etc/opendkim/keys/example.com/default.private
+To get the information you need for the DNS record, you can run ''sudo cat /etc/opendkim/keys/example.com/default.txt'' and then copy everything between the parentheses into your TXT record with ''default._domainkey'' as the host. After the DKIM TXT record caches, test it as follows:
+  sudo opendkim-testkey -d example.com -s default -vvv
+Note that that output will display "key not secure" unless you configure DNSSEC, which this tutorial has not done. It's now time to configure postfix to leverage this DKIM key. Let's make a directory for the socket and set up the configuration:
+  sudo mkdir /var/spool/postfix/opendkim
+  sudo chown opendkim:postfix /var/spool/postfix/opendkim
+  sudo nano /etc/opendkim.conf
+In the dkim config file, enter:
+  Socket    local:/var/spool/postfix/opendkim/opendkim.sock
+After establishing the socket directory and location, let's configure our dkim defaults in ''sudo nano /etc/default/opendkim'' and editing:
+  SOCKET="local:/var/spool/postfix/opendkim/opendkim.sock"
+Lastly, we need to configure postfix to be able to use opendkim in ''sudo nano /etc/postfix/main.cf'' by editing:
+  milter_default_action = accept
+  milter_protocol = 6
+  smtpd_milters = local:opendkim/opendkim.sock
+  non_smtpd_milters = $smtpd_milters
+In addition to spf and dkim policies, it's also best practice to have a dmarc policy. Let's install opendmarc with ''sudo apt install opendmarc'' and make sure to say no to db configure in the ncurses prompt, after which you should open ''sudo nano /etc/opendmarc.conf'' and enter something like:
+  AuthservID OpenDMARC
+  TrustedAuthservIDs mail.yourdomain.com
+  RejectFailures true
+  IgnoreAuthenticatedClients true
+  RequireHeaders true
+  SPFSelfValidate true
+  Socket local:/var/spool/postfix/opendmarc/opendmarc.sock
+The opendmarc socket also needs its directory created, similar to dkim. So let's create a directory for it ''sudo mkdir -p /var/spool/postfix/opendmarc'' and then set permissions and restart the service:
+  sudo chown opendmarc:opendmarc /var/spool/postfix/opendmarc -R
+  sudo chmod 750 /var/spool/postfix/opendmarc/ -R
+  sudo adduser postfix opendmarc
+  sudo systemctl restart opendmarc
+Now, we need to configure postfix to work with openDMARC. Expand the milter to include openDMARC's socket by opening ''sudo nano /etc/postfix/main.cf'' and adjusting the following block:
+  milter_default_action = accept
+  milter_protocol = 6
+  smtpd_milters = local:opendkim/opendkim.sock,local:opendmarc/opendmarc.sock
+  non_smtpd_milters = $smtpd_milters
+It's about time to setup spam controls, but before we do that, we need to make sure mission critical IMAP folders populate on clients. Let's open ''sudo nano /etc/dovecot/conf.d/15-mailboxes.conf'' and enter the auto-create line on folders that you need:
+  mailbox Drafts {
+    **auto = create**
+    special_use = \Drafts
+  }
+Since I use lmtp, which is case-sensitive, and sends incoming mail to dovecot, which is also case-sensitive, I created virtual aliases in order to avoid emails being rejected when auto-mailers capitalize or otherwise punctuate the email user name. Let's open ''sudo nano /etc/postfix/main.cf'' and add another block:
+  virtual_alias_maps = regexp:/etc/postfix/virtual_alias
+After you enter that block, let's open the file ''sudo nano /etc/postfix/virtual_alias'' and edit it with every spelling combination. Here's an example:
+  /^[Jj][Oo][Nn][Aa][Tt][Hh][Aa][Nn]@haacksnetworking.org/                jonathan
+  /^[Ww][Ee][Bb][Mm][Aa][Ss][Tt][Ee][Rr]@haacksnetworking.org/            webmaster
+It's super important to include the domain above after the regex or all emails you send to that begin with your user name will wind up in that user's inbox. When finished configuring, run ''postmap /etc/postfix/virtual_alias'' to honor the changes. So long as everything is working, we can now setup a very reasonable and appropriate way to manage spam, without playing wack-a-mole and without rejecting or discarding emails. Let's first discuss what we can do with postfix itself. It can be configured to reject or discard very poor health emails, such as but not exclusive to setting PTR rules or other fundamentals in ''sudo nano /etc/postfix/main.cf'' as follows:
+  smtpd_sender_restrictions =
+      permit_mynetworks,
+      permit_sasl_authenticated,
+      #reject_unknown_reverse_client_hostname,
+      #reject_unknown_client_hostname,
+      #reject_unknown_sender_domain,
+      #reject_unauthenticated_sender_login_mismatch,
+      reject_sender_login_mismatch
+      permit
+Personally, I disable most of the above rejects by design. I include them here more for others' reference. Just remember, there's nothing worse than never getting an email. You can also have postfix do expression checking with ''sudo apt install postfix-pcre'' and then edit ''sudo nano /etc/postfix/main.cf'' with expression checking, for example:
+  header_checks = pcre:/etc/postfix/header_checks
+  body_checks = pcre:/etc/postfix/body_checks
+In these locations, ''sudo nano /etc/postfix/header_checks'' and ''sudo nano /etc/postfix/body_checks'', setup expression checks as follows:
+  /free mortgage quote/    REJECT
+  /free mortgage quote/    DISCARD
+Once they are to your liking, make sure to compile them with ''sudo postmap /etc/postfix/body_checks'' and ''sudo postmap /etc/postfix/header_checks''. Again, in my personal setup, I keep postfix out of the spam-management game. Instead, I prefer to accept ALL email and let spam assassin do the lifting. Let's install spamassasin and integrate it with dovecot's managesieve plugin. Let's do ''sudo apt install dovecot-sieve dovecot-managesieved spamassassin spamc spamass-milter'' and then edit ''sudo nano /etc/dovecot/dovecot.conf'' as follows:
+  protocols = imap lmtp sieve
+In ''sudo nano /etc/dovecot/conf.d/15-lda.conf'' please adjust the local delivery agent as follows:
+  protocol lda {
+    mail_plugins = $mail_plugins sieve
+  }
+Let's also adjust the lmtp agent in ''sudo nano /etc/dovecot/conf.d/20-lmtp.conf'' as follows:
+  protocol lmtp {
+    mail_plugins = quota sieve
+  }
+Now it's time to setup spamassassin in postfix with the other milters. Let's open ''sudo nano /etc/postfix/main.cf'' and adjust the milter block once again:
+  milter_default_action = accept
+  milter_protocol = 6
+  smtpd_milters = local:opendkim/opendkim.sock,local:opendmarc/opendmarc.sock,local:spamass/spamass.sock
+  non_smtpd_milters = $smtpd_milters
+It's now time to edit spam assassin's default configuration file in ''sudo nano /etc/default/spamass-milter''. As with elsewhere, I make sure the REJECT line is commented out, in order to ensure that false positives won't happen. If you understand the risks and want to reject emails at the gate, go ahead and edit ''sudo nano /etc/default/spamass-milter'' and uncomment these lines:
+  #optional custom message
+  #OPTIONS="-u spamass-milter -i 127.0.0.1 -R SPAM_ARE_NOT_ALLOWED_HERE"
+  OPTIONS="-u spamass-milter -i 127.0.0.1"
+  #Reject emails with spamassassin scores > 15 [or desired score]
+  OPTIONS="${OPTIONS} -r 15"
+Again, I do not use the reject or discard options but rather leverage spam assassin's scoring and header assessing together with dovecot, which can move emails to locations fitting their scores. There are two fundamental ways to configure the scoring and sieve rules, either with the CLI or with Roundcube. When I first began, I used the CLI and created a simple rule in ''sudo nano /etc/dovecot/conf.d/90-sieve.conf'' and entered this block:
+  sieve_before = /var/mail/SpamToJunk.sieve
+The sieve_before rule ensures spam assassin assesses the email right after they arrive and before sending them to dovecot and its configured delivery agents. Let's open ''sudo nano /var/mail/SpamToJunk.sieve'' and enter the following:
+  require "fileinto";
+  if header :contains "X-Spam-Flag" "YES"
+  {
+    fileinto "Junk";
+    stop;
+  }
+After creating the sieve rule, compile it.
+  sudo sievec /var/mail/SpamToJunk.sieve
+This rule does one thing. It checks whether spam assassin identified the message as spam, and if so, it uses dovecot to file it in Junk. This means your spam assassin scores and config are what drive the success rate of this sieve rule. It's also important to note that this rule is global, and impacts all user names on the mail server. It's a good approach for the most heinous spam, leaving more customized rules to roundcube's sieve implementation, later in this tutorial. Let's open ''sudo nano /etc/spamassassin/local.cf'' and adjust it as follows.
+  report_contact webmaster@domain.com
+  #adjust score below to your use-case
+  required_score 5.0
+  #rewrite_header Subject **Possible Spam**
+  report_safe 0
+  add_header all Spam-Flag _YESNO_
+  add_header all Score _SCORE_
+  add_header all Report _REPORT_
+  add_header all Level _STARS_
+  add_header all Status "_YESNO_, score=_SCORE_ required=_REQD_ tests=_TESTS_ autolearn=_AUTOLEARN_ version=_VERSION_"
+  add_header all Checker-Version "SpamAssassin _VERSION_ (_DATE_) on _HOSTNAME_"
+  #legacy/deprecated header config - do not use, retained for historical record
+  #always_add_headers = 1
+I included some header options, which can help with debugging. Also, I disable safe reporting and Subject rewriting because they alter the original email, which I think is overkill. In order to activate all that spam assassin can do, we need to have our own recursive DNS resolver, required by RBL services. Let's use the DNS server unbound and install it as follows ''sudo apt install unbound''. It works out of the box, but you can also tweak it by looking at my tutorial here: [[https://wiki.haacksnetworking.org/doku.php?id=computing:unbounddns|Unbound DNS]]. Okay, let's now insruct spamassassin to use our dns server by opening ''sudo nano /etc/spamassassin/local.cf'' and entering the DNS server. We will also add some common scores and white and black lists while at it.
+  dns_server 127.0.0.1
+  score MISSING_FROM                      5.0
+  score MISSING_DATE                      5.0
+  score MISSING_HEADERS                   3.0
+  score PDS_FROM_2_EMAILS                 3.0
+  score FREEMAIL_FORGED_REPLYTO           3.5
+  score DKIM_ADSP_NXDOMAIN                5.0
+  score FORGED_GMAIL_RCVD                 2.5
+  score FREEMAIL_FORGED_FROMDOMAIN        3.0
+  score HEADER_FROM_DIFFERENT_DOMAINS     3.0
+  score FREEMAIL_FROM                     3.0
+  score ACCT_PHISHING                     3.0
+  score AD_PREFS                          3.0
+  score ADMAIL                            3.0
+  score ADMITS_SPAM                       3.0
+  score CONFIRMED_FORGED                  3.0
+  score FROM_PAYPAL_SPOOF                 3.0
+  score SPF_SOFTFAIL                      2.0
+  score SPF_FAIL                          5.0
+  whitelist_from *@statefarm.com
+  blacklist_from *@email.freethinkerdaily.com
+Additionally, if you check the full headers, you will see that the RBLs can now be queried without issue. Note that whitelisting adds a -100 score and that blacklisting adds a +100 score. To understand how to tweak the symbolic headers better, one should review their spam and headers periodically and update rules based on the headers you see in the full message source. Make sure to compile the sieve file with ''sievec'' each time you adjust the config, and restart postfix and dovecot. This approach above is good to do for egregiously bad email, but individual users will likely need their own controls. So, for larger servers, you can alternately use Roundcube instead. Remember, you must pick one or the other because the ''sieve_before'' rules above will bypass Roundcube's sieve logic. Bearing this in mind, if you want to use Roundcube for sieve rules, let's navigate to roundcube > settings > filters > edit filter set. To replicate similar functionality as above, I created the following:
+  require ["fileinto"];
+  # rule:[whitelist]
+  if anyof (
+      header :contains "from" [
+          "noreply@dmarc.yahoo.com",
+          "noreply@dmarc.google.com",
+          "Friend@protonmail.com"
+      ]
+  ) {
+      keep;
+      stop;
+  }
+  # rule:[blacklist]
+  if anyof (
+      header :contains "from" [
+          "awakening-minds.com",
+          "porn@yahoo.com",
+          "bounce-1.public.govdelivery.com"
+      ]
+  ) {
+      fileinto "Junk";
+      stop;
+  }
+  # rule:[spamcheck]
+  if anyof (
+      header :contains "x-spam-status" "Yes",
+      header :contains "x-spam-flag" "YES",
+      header :contains "x-spam-level" "*****"
+  ) {
+      fileinto "Junk";
+      stop;
+  }
+These rules are processed sequentially. Monitor the Junk folder periodically and refine whitelists as needed. If something escapes, like a full health dirty marketing scam, adjust your blacklist. That's all there is to it. Now that spam controls are setup, we need to setup some auditing tools to monitor how well our server is doing these tasks. For postfix, that tool is pflogsumm. Let's install it with ''sudo apt install pflogsumm'' and let's use rsyslog and log rotate to manage the logs, requiring us to also install rsyslog with ''sudo apt install rsyslog''
+Disable the ''/var/log/mail.log'' entries that are in the ''rsyslog'' logrotate rule in ''/etc/logrotate.d/''. This is because we are going to make our own logrotate rule that works nicely with pflogsumm. Create the file ''sudo nano postfix-log'' inside ''/etc/logrotate.d/'' and enter the following:
+  /var/log/mail.log {
+      missingok
+      daily
+      rotate 7
+      create
+      compress
+      start 0
+  }
+Once that's done, let's create script and cronjob to send us daily reports by creating a file ''sudo nano /usr/local/bin/pflog-run.sh'' and entering something like:
+  #!/bin/sh
+  #/usr/sbin/logrotate -f /etc/logrotate.d/postfix-log [helpful for manual testing]
+  gunzip /var/log/mail.log.0.gz
+  /usr/sbin/pflogsumm /var/log/mail.log.0 --problems-first --rej-add-from --verbose-msg-detail -q |  mail -s "[pflog-lastlog]-$(hostname -f)-$(date)" email@email.com
+  gzip /var/log/mail.log.0
+  sleep 2s
+  systemctl restart rsyslog
+  systemctl restart postfix
+  systemctl restart dovecot
+  exit 0
+The key here is that your script and zip and unzipping rules match the retention and naming conventions specified in logrotate. Since I floored the rotation at 0, the script always unzips the ''0.gz'' log. This is why it is preferable and easier to remove the ''mail.log'' stanza from the other rotations. This allows one to easily customize it for email logs without messing with other rotations and settings. Once that's done, set up a cronjob and you are all set.
+12 * * * /bin/bash /usr/local/bin/pflog-run.sh >> /home/logs/pflog-run.log
+You can also use the ''-d yesterday'' flag in pflogsumm and wildcard your domains, which I later found out. But, this works too and I retain its use in my production servers. This ends our primary configuration. If you don't have Roundcube setup, look here: [[https://wiki.haacksnetworking.org/doku.php?id=computing:roundcube|Roundcube Tutorial]]. The rest of this tutorial is miscellaneous information that has come up along the way.
+-------------------------------------------
+The SASL module packages should be brought in as dependencies of postfix and/or dovecot. However, on upgrades, etc., they might be removed during dependency resolution. If you get "no sasl" report on your logs suddenly, despite everything working prior, use:
+  sudo apt-get install libsasl2-modules
+If/when things are going wrong, turn on your detailed debugging logs and study them:
+  nano /etc/dovecot/conf.d/10-logging.conf
+  <mail_debug yes>
+To check record health after you set your DNS records, you can do the following:
+  dig txt +short _dmarc.jonathanhaack.com
+  dig txt +short _dmarc.haacksnetworking.org
+  dig default._domainkey.jonathanhaack.com txt
+  dig default._domainkey.haacksnetworking.org txt
+  dig txt +short jonathanhaack.com
+  dig txt +short haacksnetworking.org
+  dig -x 8.28.86.130 +short
+  dig -x 8.28.86.125 +short
+  sudo opendkim-testkey -d jonathanhaack.com -s default -vvv
+  sudo opendkim-testkey -d haacksnetworking.org -s default -vvv
+You should test email health with the CLI and/or use a service like [[https://www.mail-tester.com/|Mail Tester]]. I recommend using both CLI to send email and a common client. Both domain.com and mail.domain.com should work if you set everything right. Here's how to send a simple email at the CLI:
+  echo "Hi, I am testing the subdomain email health." | mail -s "CLI Email Test" oemb1905@jonathanhaack.com
+Postfix has its own CLI control tools, such as but not exclusive to viewing email, deleting email, etc.:
+  mailq
+  postcat -q E900C4780073
+  postsuper -d E900C4780073
+  postsuper -d ALL
+These tools prove helpful if/when emails get stuck, etc.
- --- //[[jonathan@haacksnetworking.org|oemb1905]] 2022/12/05 21:03//
+ --- //[[alerts@haacksnetworking.org|oemb1905]] 2025/04/23 20:54//

Haack's Wiki

User Tools

Site Tools

Differences

Page Tools