CODEWITHSUNDEEP
exchange-serveroffice365
Krzysztof S.
Krzysztof S.

Reputation: 185

Catch All rule - how to catch all emails that has been sent to not existing email address

I have a task to create a new rule that must catch all email messages which will be send to domain with exception - this rule can not concerns existing users.

For example:

I have three users:

[email protected]

[email protected]

[email protected]

When somebody will send any email message to [email protected], [email protected]... all emails send to this addresses will be redirected to [email protected].

In brief - when somebody send email on address that not exist in this domain, this message will be send to address [email protected]

Upvotes: 3

Views: 13994

Answers (4)

Massimo
Massimo

Reputation: 1540

As per Brian's answer, you'll need to create a transport rule which redirects all messages to unknown users in your domain to the catch-all mailbox.

However, you'll also need to configure the domain as an internal relay domain, as opposed to an authoritative domain; otherwise, Exchange will reject messages addressed to non-existent users before even starting to process the transport rules.

Upvotes: 3

Stefan Profanter
Stefan Profanter

Reputation: 6866

There's a CatchAll Agent for Exchange (2007, 2010, 2013) available on github: https://github.com/Pro/exchange-catchall

This one rewrites the RCPT TO so it doesn't matter if the recipient exists, the mail will be cought.

Here you can define a subdomain or also the main domain and redirect all non existing mail adresses to a specific user.

Upvotes: 0

Lucian Wischik
Lucian Wischik

Reputation: 2336

I believe that Brian's answer doesn't work. That's because

(1) You said you wanted your rule to apply to users who do not already exist (2) Transport Rules are only fired after recipients have been identified

So, if an email comes in for a recipient who doesn't exist, then the transport agent won't even get around to firing its rule.

(Well, I've not been able to get this solution to work).

Upvotes: 4

Brian Desmond
Brian Desmond

Reputation: 4503

You can do this with a Transport Rule if you have something like an All Users group that contains all your valid users/groups/etc in the domain. Essentially you will create a transport rule that says "Redirect messages to if the message is from except if ". You'll also need to disable the Recipient filtering anti-spam rule.

Generally speaking, though, this is a bad idea. You're creating a mailbox that is going to be absolutely flooded with spam, will take alot of disk space, and will need constant cleanup. Make sure the mailbox has a quota. If you get hit with a deluge of spam, you don't want this mailbox to use up all the disk space on the server and terminate service for your end user community.

Upvotes: 1

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