If the problem really is only limited to email attachments, then take a look at the email server connectivity. It may be possible that a nic has started to go bad, or perhaps the speed or duplex setting might need changing.
What makes this so weird, is it's only email attachments at ONE site. The same email server is responsible for email to all sites, including 3 other remotes which are not having this problem. That's why I'm so confused!
