cpanel emails from server with no email accounts fail
I have a problem with a cpanel server (cpanel.test.zzz) that has no email accounts setup on it. It does have valid spf, dkim and dmarc records for this domain.
In the Basic WebHost Manager® Setup and in the Contact Manager (email) and in the Edit System Mail Preferences I have a known good email on another system. serveradmin@xxx.com
This server also has valid spf, dkim and dmarc records for this domain.
All the emails from this server to the known good email fail are rejected.
[root@resellers ~]# exinext xxx.com
Route: serveradmin@xxx.com:<> error -44: H=lastmx.spamexperts.net [n.n.n.n]: SMTP error from remote mail server after RCPT TO:<serveradmin@xxx.com>: 451 unable to verify user
first failed: 19-Apr-2025 18:31:47
last tried: 17-May-2025 18:07:57
next try at: 18-May-2025 02:07:57
past final cutoff time
Route: serveradmin@xxx.com:<cpanel@cpanel.test.zzz> error -44: H=lastmx.spamexperts.net [n.n.n.n]: SMTP error from remote mail server after RCPT TO:<serveradmin@xxx.com>: 451 unable to verify user
first failed: 17-May-2025 17:58:28
last tried: 18-May-2025 10:01:30
next try at: 18-May-2025 18:01:30
Route: serveradmin@xxx.com:<postmaster@yyy.com> error -44: H=lastmx.spamexperts.net [n.n.n.n]: SMTP error from remote mail server after RCPT TO:<serveradmin@xxx.com>: 451 unable to verify user
first failed: 18-Apr-2025 03:28:11
last tried: 20-May-2025 17:49:10
next try at: 21-May-2025 01:49:10
past final cutoff time
Route: serveradmin@xxx.com:<cpanel@whmcs.test.zzz> error -44: H=lastmx.spamexperts.net [n.n.n.n]: SMTP error from remote mail server after RCPT TO:<serveradmin@xxx.com>: 451 unable to verify user
first failed: 18-Apr-2025 18:20:29
last tried: 22-Apr-2025 18:38:00
next try at: 23-Apr-2025 02:38:00
past final cutoff time
Route: serveradmin@xxx.com:<root@cpanel.test.zzz> error -44: H=lastmx.spamexperts.net [n.n.n.n]: SMTP error from remote mail server after RCPT TO:<serveradmin@xxx.com>: 451 unable to verify user
first failed: 17-Apr-2025 04:34:09
last tried: 20-May-2025 21:09:53
next try at: 21-May-2025 05:09:53
past final cutoff time
Route: serveradmin@xxx.com:<serveradmin@cpanel.test.zzz> error -44: H=lastmx.spamexperts.net [n.n.n.n]: SMTP error from remote mail server after RCPT TO:<serveradmin@xxx.com>: 451 unable to verify user
first failed: 18-May-2025 15:05:09
last tried: 20-May-2025 16:53:22
next try at: 21-May-2025 00:53:22
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Hey there! Did the original Exim log entries show that the retry time was not reached? If so, being a server with no email accounts, this would most likely be an issue with the local resolvers not being able to look up the remote mailserver.
Are you able to run a basic "dig mx domain.com" from that machine, where "domain.com" is the domain you're trying to send messages to?
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Maybe that "451 unable to verify user" error is because there is "Sender Verification Callouts" On in the receiving server?
"Use callouts to verify the existence of email senders. Exim will connect to the mail exchanger for a given address to verify it exists before accepting mail from it."
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cPRex
$ dig mx receiver.com +short
10 _dc-mx.dd4b09d3c056.receiver.com.
20 _dc-mx.11302ce2cf04.receiver.com.Couple of things I don't get here.
1. The receiving server does exist, has proper DNS, has a mailbox ... I can send mail to it from, ex. a hotmail address
2. If the sending server has no mailboxes, "who" is sending the email from sender.com? What kind of DNS is required?
quietFinn
Thanks, Not sure I want to drop that on the receiving server right now, as there are a lot of other accounts there.
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I guess I'm not fully understanding the issue. How are you testing email when there are no mailboxes configured? Are these system level notifications?
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Yes I am only wanting to receive cpanel notices, system notifications.
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I think it's quite common configuration, that root emails are sent from, like "serveradmin@xxx.com", but that email does not exist in the sending server.
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