A user got the following message today when sending email to one domain. However the messages has arrived to at least 3 of the recipients, which the user confirmed by telephone.
I tried to google it, but only found that 552 means the message was too large, which doesn't seem probable since it has been received.
There was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<ourDomain #5.5.0 smtp;552 Unable to process message:
msg.1236927854.923664.5617 - error: recipient: user1@theirDomain failed, reason: Giving up on theirIP. 550 user1@theirDomain... No such user, recipient: user2@theirDomain failed, reason: Giving up on theirIP. 550 user2@theirDomain... No such user, recipient: user3@theirDomain failed, reason: Giving up on theirIP. 550 user3@theirDomain... No such user>
The colleague is out to lunch, but I will double check when she got back that the recipients that received the message are the once that are included in the error message.