Correct rDNS / HELO when using /etc/mailhelo and /etc/mailips ?

Arkaic

Active Member
Jun 23, 2015
35
5
58
United Kingdom
cPanel Access Level
Root Administrator
The issue
In cPanel -> Email Deliverability for domain1.co.uk it shows:

"Problems Exist (Reverse DNS)"

The system sends “domain1.co.uk”’s outgoing email from the “10.10.10.5” IP address. The only PTR value for this IP address must be “domain1.co.uk”. This is the name that this server sends with SMTP’s “HELO” command to send “domain1.co.uk”’s outgoing email.

1 unexpected PTR value exists for this IP address:

my.serverhostname.co.uk
To fix this problem, contact your system administrator and request that they replace all PTR records for “*****” with the following record at “*****” and “*****”

/etc/mailhelo looks like this:
domain1.co.uk: domain1.co.uk
domain2.co.uk: domain2.co.uk
domain3.co.uk: domain3.co.uk
*: my.serverhostname.co.uk

/etc/mailips looks like this
domain1.co.uk: 10.10.10.5
domain2.co.uk: 10.10.10.5
domain3.co.uk: 10.10.10.5
*: 10.10.10.2

10.10.10.2 is the main IP address of the server with perhaps bad reputation
10.10.10.5 is an additional IP address of the server with no sending issues.


Is the warning shown in cPanel Email Deliverability an actual issue? Is there another setting that perhaps needs changing?
The rDNS for the IP address is set to the hostname. As there are multiple domains sending from that IP we cannot set the rDNS to be that of the domains sending mail on that IP.
Or should the domains be HELO'ing from the hostname instead? Which isn't ideal because it resolves to a different IP address than the mail it is sent out from.
 
Last edited by a moderator:

cPRex

Jurassic Moderator
Staff member
Oct 19, 2014
4,357
546
273
cPanel Access Level
Root Administrator
Hey there! If 10.10.10.5 doesn't have any sending issues, wouldn't it be easier to have every domain send from there instead of just domain1-3? Then you could just change the main IP to the 10.10.10.5 IP and not worry about any misconfigurations.

In general, the hostname will still show up in the mail headers no matter what makes the "helo" call, so if the rDNS is properly pointed to the hostname I would expect things to work.