I am setting up a testing server for a web based application that sends some email notifications.

Sometimes testing is performed with real customer data, and for that reason I need to guarantee that the server is not able to send emails to our real customers while we're testing.

What I want is to configure postfix so that it takes any outgoing email and redirects it to a single email address, instead of delivering to the real destination.

I am running Ubuntu server 9.10.

Thank you in advance


Set up a local user to receive all trapped mail:

adduser mailtrap

You need to add in main.cf:

transport_maps = hash:/etc/postfix/transport
luser_relay = mailtrap

Then create /etc/postfix/transport with this in there:

localhost :
* local:mailtrap

Save an then run: postmap /etc/postfix/transport finally restart postfix invoke-rc.d postfix restart

All local email will be delivered normally and external email will be delivered to the local mailtrap account.

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  • This is exactly what I was looking for... thank you! – 0x6A75616E Feb 12 '10 at 23:29
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    Works for me but only after I added luser_relay = xxxxx in main.cf. Without this the emails would bounce. – Alex R May 29 '11 at 0:57
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    When using Ubuntu, you can also restart Postfix with sudo service postfix restart. The location of your main.cf file mentioned above is /etc/postfix/main.cf. When first installing and setting up Postfix, you can use the Local only installation option. – mtnorthrop May 25 '12 at 9:12
  • on MAC you should run postmap hash:/etc/postfix/transport and sudo postfix stop, sudo postfix start – Bang Dao Jul 23 '13 at 8:50
  • this is great. does anyone know how to eliminate duplicates when a message has multiple recipients? – graywh Mar 21 '18 at 18:33

Better is to create a virtual alias file:

In /etc/postfix/main.cf:

virtual_alias_maps = pcre:/etc/postfix/virtual

In /etc/postfix/virtual:

/.*@.*/ root

You can replace root with whichever user you'd like to receive all the outgoing e-mail. This pattern can be tweaked if you want local mail to be delivered normally (without redirection):

/.*@(?!hostname\.localdomain$).*/ root

Original idea found here: Postfix development server - intercept all outgoing mail

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  • 2
    Note you might need to sudo apt-get install postfix-pcre beforehand, to avoid… surprises. – mirabilos Jun 15 '15 at 14:01
  • works for me very well! – michael-mammut Jan 12 '17 at 10:00
  • error "User unknown in virtual alias table" – Alex R May 16 '17 at 22:36

Postfix provides something called smtp-sink. By default it blackholes all of the email it receives. Later versions can also be configured to capture the email in files.

This doesn't technically use postfix (but a utility provided by postfix.) It also doesn't technically redirect each email to a single email address. But it does capture all traffic on port 25 and dumps that to a file that can be parsed.

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  • How does one invoke smtp-sink? The one manpage I found online made it look like it's a normal program, but if it came with postfix it's not installed on my system (OSX 10.6). How would I run this a service? – Chris Bloom Nov 22 '10 at 1:26
  • There is a manpage for smtp-sink. But some parameters are described here, too: blog.malowa.de/2011/04/postfix-as-spam-trap-server.html – mailq Aug 16 '11 at 9:30

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