Messaging Gateway

One of my users reports that when he is sending an email to one particular client (outside the network) the client receives the Symantec Qurantined email stating emails have been qurantined (strange). Why would this happend for outbound emails?

Any advice is will be appreciated.

Are you saying the outbound e-mail from your.user to external client/recipient is quarantined on YOUR Brightmail box?   Or is it part of the recipient's mail system that's doing the quarantining?

Does it matter what is in the e-mail?  HTML vs plain text? Any attachments? For example,  Office 2007 docs are actually .ZIP files and can include binary data (.bin) files.  Some incorrectly AV systems detect these as suspect virus.

Yes outbound emails from our system to the external client are qurantined and then emailed to the user on OUR brightmail box.

Only 1 user is affected when sending emails to this particular domain.

Yes there are some attachements and some are not.

What do the message audit logs show?