Double email address

This has been happening for a long time/am trying to sort it out - following is an actual error email 'as is' other than domain and subject 'removed' - can anyone shed any light please? Thanks!

*** Errors occurred while processing the attached Email.
You should process this Email manually.

Reason:
Fields with illegal values:
Invalid email address received for the Ticket Recipients data field (customerservice@mbna.co.ukautoreply@customerservi ce.mbna.co.uk).

----- Original Message -----
From: "CustomerService@MBNA.co.uk" <CustomerService@MBNA.co.uk>
Sent: Tue, 4 Feb 2014 17:12:23 +0100 (CET)
To: support@removed
Subject: removed

That ticket recipient field doesn't look right, please send us your logs for further analysis: Help > Technical Support > Send Log Files.

We've just emailed you a small patch to apply that should resolve this scenario.