# Postfix/cyrus sender notification if a mailbox doesn't exist

## z0ny

Hello, I am running a postfix/cyrus setup for handling mails. Is there a way to not notify the sender if a mailbox doesn't exist (for spam reasons)? Thanks.

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## cach0rr0

easiest way?

disable checks of local_recipient_maps, then set up luser_relay to go to a blackhole account (you'll have to arrange your own way for clearing this box out)

when I say disable local_recipient_maps, i mean set something like this in your main.cf

```

local_recipient_maps=

luser_relay=blackhole@yourdomain.com

```

yes, literally with nothing after the = sign

more reading:

http://www.postfix.org/postconf.5.html#luser_relay

http://www.postfix.org/postconf.5.html#local_recipient_maps

You would need to set up the blackhole mailbox in Cyrus before you did this, else you'd have cyrus rejecting the message at the post-acceptance LMTP phase, and end up generating backscatter. 

Maybe there's a better way of doing this, but that's the quickest one that comes to mind. Postfix has loads of configuration options that'll reach this goal, in varying ways. 

You could even set this http://www.postfix.org/postconf.5.html#smtpd_hard_error_limit

EDIT: actually, this is a really good read that outlines some of the pitfalls involved in doing this. I agree with their final conclusion, too, you probably aren't gaining much by not sending a 550 for invalid addresses - http://www.irbs.net/internet/postfix/0502/1581.html

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