Query on badmail/ undelivered mail

kam_uk used Ask the Experts™

Let's say mail to a recipient flows in this manner:

Exchange 1 > MTA1 > MTA2 > Exchange2

For some reason, Exchange2 is down, and it is down for all of MTA2's retry period.

What happens to the actual message? I know MTA2 sends an NDR back to the address in the return-path, however - say there was a 10MB attachment with the mail, where does this actually go?

My assumption was that it would go the Badmail directory on MTA2...does it ever get deleted from there? Do SMTP servers like Exchange and IIS SMTP have defaults for deleting messages from the badmail queue, otherwise surely it would get so large eventually and fill the drive?
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IT Infrastructure Architect
The Badmail folder contains messages that cannot be delivered into your organisation, and also cannot be returned back to the sender. So, the folder usually contains spam.

If the mails have a valid sender address, server will send back NDR to sender address after a time period which is configured in the SMTP virtual server and a NDR will be send back to sender address. Normally the original mail will be send with NDR as an attachment, which can be voided.



Ah ok - so the Badmail is only for mail that cannot be returned? If the mail cannot be sent, then usually the entire message is sent back to the sender?

Do know where the option is to set this (i.e. whether the NDR contains the actual message)?

Subash SundharanIT Infrastructure Architect

Please refer MS KB 308303 In my last post..

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