DKIM Signature Alignment issue for emails relayed through the server

[CJRB]

I'm going to try to explain the issue that we are experiencing and maybe someone had similar issue and have properly configured Zone entries.

We have 2 domains (examples):
1. sharedhosting.com - This domain is hosted on a shared hosting where we have our main website and ticketing system (osTicket) hosted. Cpanel user access only.
2. dedicatedserver.com - This domain is hosted on our dedicated server with WHM/Cpanel access and is used for our web application.

Since our emails from sharedhosting.com would end up in JUNK or SPAM folder because our account would use shared mail server we decided to send emails from our dedicatedserver.com as it has good reputation.

We created [email protected] email address and configured our ticketing system to send emails through that account with authentication with the FROM header "[email protected]". We configured SPF records on dedicatedserver.com to include sharedhosting.com.

osTicket ([email protected]) --> DedicatedServer.com (via [email protected]) ---> Recepient
Recepient reply ---> [email protected] (on sharedhosting.com)

Upon checking email deliverability on MXTools.com the only issue that came up was error for:
DKIM Signature Alignment
"DKIM Alignment hinges the domain in your "FROM" header matching the domain used in the DKIM signature (d=domain.com). This uses a relaxed format by default which means that a sub-domain would align as well. If this value is changed to strict in your DMARC record then the domain must match exactly.
If there are multiple DKIM signatures, only one of them must align for DKIM alignment to be valid."

From my understanding we need to add one more DKIM for our sharedhosting.com domain to our dedcatedserver.com so that it will email both DKIM signatures so that emails sent with FROM header "[email protected]" would not trigger that error.

Is there a way to add DKIM signature and should we copy the signature that is set on sharedhosting.com or create a new one?

Any help with this issue is greatly appreciated and hopefully will help other users.
Thanks

 

[cPRex]

Hey there! If I'm understanding this correctly, you'd want to copy over the record from the sharedhosting.com DNS zone. Can you try that and see if that gets things working how you expect?

 

[CJRB]

Hey there! If I'm understanding this correctly, you'd want to copy over the record from the sharedhosting.com DNS zone. Can you try that and see if that gets things working how you expect?

Yeah, I'm trying to figure out where to copy those records in cPanel account properly.

So there is default DKIM record on "sharedhosting.com" under default._domainkey.sharedhosting.com. So I tried to duplicate that record under Zone Editor on dedicatedserver.com as s1._domainkey.dedicatedserver.com but it doesn't seem to add that DKIM it only sets "default" DKIM 0_o. I'm not sure whether I'm addigin it correctly under s1 domain key or I should add it under different domainkey.
I also have access to WHM - so maybe there is setting to embed additional key beside default key?

 

[cPRex]

Unfortunately there isn't a way to add anything other than the default key:

https://features.cpanel.net/topic/dkim-support-for-custom-selector

It might be best to create a ticket on this issue so we can see everything in action, as there seems to be a lot of moving parts here between the two systems.