It's been awhile,

Try

sudo amavisd-new showkeys

Once you generated the Key you need to add it as a TXT Record.

Name dkim_domainkey
Value v=DKIM1; p= Key_from_amavis_output

For multiple domains,
sudo nano /etc/amavis/conf.d/50-user

Find the line with domain0 of course your domain,
dkim_key('domain0.com', 'dkim', '/var/lib/dkim/domain0.com.pem');

Add the second Domain
dkim_key('domain1.com', 'dkim', '/var/lib/dkim/domain1.com.pem');

In the dkim_signature_options_bysender_maps section,
add the following
"domain1.com" => { d => "domain1.com", a => 'rsa-sha256', ttl => 10*24*3600 },

Then generate the key
sudo amavisd-new genrsa /var/lib/dkim/domain1.com.pem 2048

Restart Amavis
sudo systemctl restart amavis

Make sure to set the permissions to amavis:amavis
sudo chown amavis:amavis /var/lib/dkim/ -R

Then show the keys for the domains add the key to DNS
sudo amavisd-new showkeys

Regards

Post the output,
cd /etc/amavis/
ls -la

Regards

Some linux distros use "amavisd" as the command, but some uses "amavisd-new".

Actually, can I use the current dkim key that iRedMail generated for my domain and use it for all other domains?  If so what would I need to do?

Thanks

Well the link kind of doesn't help, because there is no amavisd.conf file anywhere to be found.  I'm really at a loss here.  I put my dkim record in my dns with the key that was generated after install, yet when I run a test on dkim for that domain it fails.

I'm really at a loss on this issue.

No leave the sample.conf alone. When you do sudo amavisd-new showkeys do you get a output ?

You only need to edit 50-user

 sudo nano /etc/amavis/conf.d/50-user
 
 Find the following line,
 
 dkim_key('domain0.com', 'dkim', '/var/lib/dkim/domain0.com.pem');
 
 Add another line with,
 
 dkim_key('domain1.com', 'dkim', '/var/lib/dkim/domain1.com.pem');
 
 look for the line dkim_signature_options_bysender_maps then add,
  
 "domain2.com" => { d => "domain2.com", a => 'rsa-sha256', ttl => 10*24*3600 },

 Once done run the following,
 
 sudo amavisd-new genrsa /var/lib/dkim/domain1.com.pem 2048

 Change Permissions,
 
 sudo chown amavis:amavis /var/lib/dkim/ -R

 Restart Amavis,
 
 sudo systemctl restart amavis

 Then run the following,
  
 sudo amavisd-new showkeys

Once you got the new keys, add a TXT Record to your Name Servers.

Regards

Are you sure you are using iRedMail? I would suggest starting from scratch and install https://www.iredmail.org/download.html

On all installations of iRedMail amavis-new has been installed.

Regards

Yep, fresh install on a Ubuntu 24.04 Staging Environment,

root@mx.stage04:/etc/amavis# ls -la
total 28
drwxr-xr-x   4 root root  4096 Aug 17 20:05 .
drwxr-xr-x 127 root root 12288 Aug 17 20:32 ..
drwxr-xr-x   2 root root  4096 Aug 17 20:06 conf.d
drwxr-xr-x   2 root root  4096 Aug 17 20:05 en_US
-rw-r--r--   1 root root   978 Jul 17  2023 README.l10n
root@mx.stage04:/etc/amavis# cd conf.d
root@mx.stage04:/etc/amavis/conf.d# ls -la
total 112
drwxr-xr-x 2 root root  4096 Aug 17 20:06 .
drwxr-xr-x 4 root root  4096 Aug 17 20:05 ..
-rw-r--r-- 1 root root  1610 Jul 17  2023 01-debian
-rw-r--r-- 1 root root   692 Jul 17  2023 05-domain_id
-rw-r--r-- 1 root root   429 Jul 17  2023 05-node_id
-rw-r--r-- 1 root root 20791 Jul 17  2023 15-av_scanners
-rw-r--r-- 1 root root   717 Jul 17  2023 15-content_filter_mode
-rw-r--r-- 1 root root  9511 Jul 17  2023 20-debian_defaults
-rw-r--r-- 1 root root   649 Jul 17  2023 21-ubuntu_defaults
-rw-r--r-- 1 root root   573 Jul 17  2023 25-amavis_helpers
-rw-r--r-- 1 root root  2130 Jul 17  2023 30-template_localization
-rw-r--r-- 1 root root  1567 Jul 17  2023 40-policy_banks
-rw-r--r-- 1 root root 29144 Aug 17 20:06 50-user
-rw-r--r-- 1 root root   318 Aug 17 20:06 50-user.2024.08.17.20.01.12

You can see the fresh install here on stag04 has Amavis & it's configs present, latest 1.7.1 as of this post.

Regards

It looks as though amavisd is the program.  I found this in /usr/sbin and ran it with -h to see if it would answer.  I also did a systemctl status amavis, this is where i found that it was amavisd that was running it.  So I assume I can just use the amavisd instead of amavisd-new.  Are the commands the same as above for using the same dkim?