If you are receiving many non-delivery emails
it may be that you have a Auto-Responder / Vacation Message enabled on
that particular email message (POP3 Account).
An Auto-Responder / Vacation Message will reply to everything including
spam. Since spammers rarely put in a valid return address, but do use a
valid mail domain, the receiving mail server will bounce the message
back to us. The Auto-Responder is set to send an automatic reply only
once per day, per email address. However, at the volume of email that
the spammers send this can be a hassle.
The recommended way to deal with this is to TEMPORARILY setup a filter
rule in your email client (e.g. MS Outlook) to send these to a
different folder or to delete them. Otherwise, you can do this using a
Content Filter in your web based email. We DO NOT recommend leaving
this rule enabled in the long term. This is because you would no longer
be able to see non-delivery reports for valid email you tried to send.
Please note, this situation can also occure if you have the Catch-All option enabled on the email address (POP3 Account).