What is problem when EU is receiving hundreds of undeliverable messages?

By Shanny1977 ·
I am running Outlook 2003 and I have end users that are receiving hundreds of undeliverable messages. What is the potential cause and possible resolution for this?

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Bouncing spam? Or even fake bounces!

by TobiF In reply to What is problem when EU i ...

First question: Is this a bounce of a legitimate message that the user sent?

If yes: the bounce will most probably contain a clear text message about what happened. (incorrect mail address, full mailbox etc.)

But, this sounds more like some spammer has be using this end users email address as a fake sender address of spam.

It's easy to fake sender address, it's just a piece of text in the header. Spammers use real addresses or rotate addresses generated on-the-fly as sender addresses. (The reason for this is, of course, that Microsoft and several other companies in their spam hunting efforts bet heavily on sender address as a useful parameter to recognize spam.

Just double check that the spam wasn't sent from your own ip addresses. Open a couple of attachments in the bounce-messages and check what was the last ip server address before the email was sent over to the receiving server. If that IP address resolves to some ADSL network in Far-Far-Away, then you can safely discard the issue. Not much else you can do.

Forgot to mention fake bounces.
Some spammer may bet that a bounce runs better chances of getting through to the user and being read. So they may try to actually deliver spam, disguised as bounces.

In other words, the whole attachment may be fake!

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