exim - unrouteable address

Operating System & Version
CentOS 7.9
cPanel & WHM Version
v100.0.5

madnoob2

Active Member
Apr 18, 2017
43
0
6
Austria
cPanel Access Level
Root Administrator
Hey,

I have a weird problem with about ~200 mails in queue being frozen, due to exim saying Unrouteable address (let's say it's [email protected]) which is really weird since from another account on the same WHM I can send emails to [email protected] without any problems.
The mails are NDR, and originating from [email protected] - ie. being sent as a root user.
exim -bt [email protected] tells me :
[email protected]
router = lookuphost, transport = remote_smtp
host domain-com.mail.protection.outlook.com [104.47.18.74] MX=0
host domain-com.mail.protection.outlook.com [104.47.17.74] MX=0

which means it can resolve the address using remote_smtp transport.
So this is quite confusing, I'm not sure why these mails are not being sent out, when the system can obviously send emails to the address...
 

madnoob2

Active Member
Apr 18, 2017
43
0
6
Austria
cPanel Access Level
Root Administrator
I found these 2 correlating ID's :
1mxBGW-00084f-Ap H=(somehost) [someip]:64182 Warning: Message has been scanned: no virus or other harmful content was found
1mxBGW-00084f-Ap <= [email protected] H=(somehost) [someip]:64182 P=esmtpsa X=TLS1.2:ECDHE-RSA-AES256-SHA384:256 CV=no A=dovecot_login:[email protected] S=40290 T="Test mail" for [email protected]
cwd=/var/spool/exim 3 args: /usr/sbin/exim -Mc 1mxBGW-00084f-Ap
1mxBGW-00084f-Ap Sender identification U=domaincom D=domain.com S=[email protected]
1mxBGW-00084f-Ap SMTP connection outbound 1639501620 1mxBGW-00084f-Ap domain.com [email protected]
1mxBGW-00084f-Ap H=mx-ha03.web.de [212.227.15.17]: SMTP error from remote mail server after RCPT TO:<[email protected]>: 450 Requested mail action not taken: mailbox unavailable
1mxBGW-00084f-Ap == [email protected] R=dkim_lookuphost T=dkim_remote_smtp defer (-44) H=mx-ha02.web.de [212.227.17.8]: SMTP error from remote mail server after RCPT TO:<[email protected]>: 450 Requested mail action not taken: mailboxunavailable
1mxBGW-00084f-Ap ** [email protected]: Unrouteable address
1mxBRc-0008jk-0Q <= <> R=1mxBGW-00084f-Ap U=mailnull P=local S=41517
1mxBGW-00084f-Ap Completed
1mxBRc-0008jk-0Q <= <> R=1mxBGW-00084f-Ap U=mailnull P=local S=41517
1mxBRc-0008jk-0Q ** [email protected]: Unrouteable address
1mxBRc-0008jk-0Q Frozen (delivery error message)
1mxBRc-0008jk-0Q Message is frozen

So, [email protected] is sending the email to [email protected], web.de responds that the email does not exist, exim marks it as unrouteable, and tries sending NDR to the sender [email protected] which also fails saying unrouteable.

Sender ([email protected]) is sending messages via exim as it's SMTP source, but domain.com MX points to a remote mailserver (outlook in this case, as mentioned above and can be seen with the exim -bt check). Also, domain.com is an account in the WHM, having it's email routing set to REMOTE.
 

quietFinn

Well-Known Member
Feb 4, 2006
1,649
323
438
Finland
cPanel Access Level
Root Administrator
When you go to WHM -> DNS Functions -> Email Routing Configuration -> domain.com
is it set to "Remote Mail Exchanger"?
 

madnoob2

Active Member
Apr 18, 2017
43
0
6
Austria
cPanel Access Level
Root Administrator
When you go to WHM -> DNS Functions -> Email Routing Configuration -> domain.com
is it set to "Remote Mail Exchanger"?
Yes it does, however there is a box below it saying MX entries and it has MX destination set to domain.com which is incorrect, the MX for domain.com is at outlook, as per DNS. Does it not query the DNS for the MX entries or do they have to be stored locally?
 

quietFinn

Well-Known Member
Feb 4, 2006
1,649
323
438
Finland
cPanel Access Level
Root Administrator
Only if it's "Local Mail Exchanger" Exim doesn't check the MX records.
Actually your 1st post in this thread shows that Exim get's the correct MX record.
is domain.com in /etc/remotedomains ?
 

madnoob2

Active Member
Apr 18, 2017
43
0
6
Austria
cPanel Access Level
Root Administrator
Only if it's "Local Mail Exchanger" Exim doesn't check the MX records.
Actually your 1st post in this thread shows that Exim get's the correct MX record.
is domain.com in /etc/remotedomains ?
Yes it is. Like I said sending from a different account in the same WHM the email goes through to the remote MX, only these NDR emails that root is trying to send are the problem...
 

cPanelAnthony

Administrator
Staff member
Oct 18, 2021
1,046
111
118
Houston, TX
cPanel Access Level
Root Administrator
Yes it is. Like I said sending from a different account in the same WHM the email goes through to the remote MX, only these NDR emails that root is trying to send are the problem...
It may be worth opening a ticket using the link in my signature and providing me with the ticket ID so I can keep this thread updated.