SOLVED Question regarding email addresses containing a "+" sign

akust0m

Well-Known Member
Feb 19, 2016
72
4
58
Melbourne
cPanel Access Level
Root Administrator
Hello,

We have a client where they have their default address set to deliver all unrouted mail to a forwarder which then is supposed to go to a real mailbox on the server.

So it goes *default account* > *forwarder* > *mailbox*.

The client has mentioned that in the past, he has had no problems with people sending emails to his domain with a + sign in it. For example: [email protected]

However, recently he has noticed that none of these emails are being received. Running an exim test returns the following:

# exim -bt [email protected]
mail to [email protected] is discarded

There seems to be no global or individual mail filters on his cPanel account.

Also, if I run the same test as above but without a "+" sign then it shows a successful delivery to the desired mailbox.

We set up an identical setup on a different cPanel server and it delivers perfectly fine through to the desired mailbox as well.

Are there any settings in Exim that would prevent the use of a "+" symbol?

Thanks!
 
Last edited:

akust0m

Well-Known Member
Feb 19, 2016
72
4
58
Melbourne
cPanel Access Level
Root Administrator
Ok so we were able to narrow down where the problem is:

In this case, the client was receiving email to "[email protected]". This email account doesn't exist, it is caught in the default mail account catch-all, which then forwards through to "[email protected]" (which is an email forwarder).

The email is discarded, however sending to "[email protected]" works.

So it seems that there is a problem when the part before the "+" sign on the email address that is being sent to matches the part before the @ symbol on the email forwarder.
 

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,904
2,218
463
Hello,

A feature to support email subaddresses was introduced in cPanel version 58:

Email subaddresses
This feature, also known as plus addressing, allows senders to route a message directly to the folder of a mailbox.

Email subaddresses use the [email protected] format, where username represents the username of the mailbox and folder represents the folder's name.

For example, if you send a message to [email protected], the mail server will route the message to the Important folder in the [email protected] mailbox.

Notes:
  • If the folder does not already exist, the system will create that folder.
  • You must subscribe to the folder in your email or webmail client for the folder to appear.
Thus, the email account name before the "+" symbol must exist on the system as an actual email account or forwarder, or else the action defined via the "Default Address" feature is utilized. Could you verify if the email account you are encountering an issue with exists on the system?

Thank you.
 

akust0m

Well-Known Member
Feb 19, 2016
72
4
58
Melbourne
cPanel Access Level
Root Administrator
Hi @cPanelMichael,

The client was wanting to receive email to "[email protected]". I don't think it was for the purpose of sub-addressing though; he just wanted a + sign in his email. This email account doesn't exist, instead it is caught in the default mail account catch-all, which then forwards through to "[email protected]".

In the above case, mail is discarded, perhaps because the folder "test" doesn't exist?? However sending to "[email protected]" works.