Setup mail forwarding in postfix on Ubuntu or Debian

Postfix mail forwarding

Postfix is a commonly used MTA (Mail Transfer Agent) program that can receive, deliver or route emails. So if you have your own domain and a server then using postfix you can setup emails on the domain like myname@mydomain.com.

Setting up a full featured mail server with postfix is a lengthy process requiring quite some effort. Furthermore, using your own mail server you do miss out the convenience and features of the popular free email services like gmail or hotmail. One way is to use google's paid service to integrate gmail with the domain email.

Alternatively, setup your webserver to forward all mails coming on your domain email, to your other address like gmail. Doing so would allow you to accept mails on your personal domain emails, making it look professional and at the same time use gmail service to access the same and enjoy the convenience of gmail too.

mail for superman@site.com ==> [ site.com Postfix server ] ==> forwarded to superman@gmail.com

So this post shows how to setup mail forwarding on a Debian or Ubuntu server using the postfix program. For other distros like CentOS and Fedora too, the steps are nearly the same.

Install Postfix

Installation is super quick. Postfix is there in the default repos, so just use apt-get to install.

$ sudo apt-get install postfix

During installation it would ask a couple of questions about how to configure the mail server. Fill in the required information and proceed. Once the installation is complete, the mail server daemon would be started.

$ sudo service postfix status
 * postfix is running

You can further check that postfix is running a server on port 25 with the netstat command

$ sudo netstat -ltnp | grep 25
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      1926/master     
tcp6       0      0 ::1:25                  :::*                    LISTEN      1926/master

The last column shows the pid of the processing, which is postfix here.

Verify DNS settings of domain

Before proceeding to configuring postfix to forward mails on behalf of your domain, its necessary to ensure that the MX records for your domain are pointing to the right server. This can be done quickly with the dig command. Run it from your local machine.

$ dig binarytides.com mx

; <<>> DiG 9.9.3-rpz2+rl.13214.22-P2-Ubuntu-1:9.9.3.dfsg.P2-4ubuntu1.1 <<>> binarytides.com mx
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7230
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;binarytides.com.               IN      MX

;; ANSWER SECTION:
binarytides.com.        85100   IN      MX      10 mail.binarytides.com.

;; Query time: 74 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Fri Mar 28 08:59:17 IST 2014
;; MSG SIZE  rcvd: 65






In the 'ANSWER SECTION' it can be seen that mail.binarytides.com is reported as the mail server for binarytides.com. Next, dig up the a records for the domain mail.binarytides.com and it would show the server ip to which it points.

$ dig mail.binarytides.com a

; <<>> DiG 9.9.3-rpz2+rl.13214.22-P2-Ubuntu-1:9.9.3.dfsg.P2-4ubuntu1.1 <<>> mail.binarytides.com a
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 43356
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;mail.binarytides.com.          IN      A

;; ANSWER SECTION:
mail.binarytides.com.   85045   IN      A       173.255.230.5

;; Query time: 30 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Fri Mar 28 09:00:19 IST 2014
;; MSG SIZE  rcvd: 65

Now the ANSWER SECTION shows the ip address of mail.binarytides.com which over here is correct. Do the same for your domain and verify that the mx records are setup correctly.

Configure postfix to forward mails

Now comes the final task of configuring postfix to forward mails, and it is surprisingly simple.
Find the path of the configuration directory using the postconf command

$  postconf | grep config_directory
config_directory = /etc/postfix

Now we know that all the necessary configuration files lie in the above directory, so get inside it.
Edit the main.cf file

/etc/postfix/main.cf

And add the following lines at the end of it

virtual_alias_domains = mydomain.com myanotherdomain.com
virtual_alias_maps = hash:/etc/postfix/virtual

The first line virtual_alias_domains lists the domains, for which postfix is going to accept emails. Multiple domains are added separated by a space.

The second line virtual_alias_maps specifies the path to the file which is going to contain mappings specifying how to forward emails for the above domains.

Now open the /etc/postfix/virtual file (create one if it does not exist) and add to it the emails you want to forward along with the destination emails.

# lets forward 2 emails

contact@mydomain.com myself@gmail.com
sales@mydomain.com myself@gmail.com

The first email is the address on which postfix shall receive emails, and the second is the address where postfix would forward the emails.

The mail can be forwarded to multiple destinations

contact@mydomain.com myself@gmail.com mystaff@gmail.com

To catch and forward emails to any address for a given domain, use the following notation

# forward all emails

@mydomain.com myself@gmail.com mystaff@gmail.com

After entering the forwarding rules, save the file and close it. Then run the following commands for the new settings to take effect

Update the postfix lookup table

$ postmap /etc/postfix/virtual

Reload postfix configuration

$ sudo /etc/init.d/postfix reload

# or

$ sudo service postfix reload

Check with the postconf command that the domain aliases and alias file have been setup properly.

$ postconf -n | grep virtual
virtual_alias_domains = mydomain.com myanotherdomain.com
virtual_alias_maps = hash:/etc/postfix/virtual
root@localhost:~#

Test it now

Now try sending an email from somewhere outside the world, to the address on your domain, and you should see the same mail forwarded to the gmail account.

Last Updated On : 8th April 2014

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16 Comments + Add Comment

  • Hi There, Great post! Thank you :) I just had one problem. I have followed your guide exactly but my emails are not being delivered. I get the following error when trying to forward email “Diagnostic-Code: X-Postfix; User unknown in virtual alias table”. Can anyone help?

  • Warning! I have encountered that with a default postfix configuration this will open your server for SPAM as it allows log in via unauthenticated locations. Dear author, please add a line on smtp restrictions!

    I have disabled SASL as it seems to be unneeded for forwarding only and disable the unauthenticated destinations for now as a first step.

    default main.cf:
    smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination

    mail.log:
    Mar 29 19:23:10 planetsofa postfix/smtpd[11118]: warning: hostname 88.249.45.76.dynamic.ttnet.com.tr does not resolve to address 88.249.45.76: Name or service not known
    Mar 29 19:23:10 planetsofa postfix/smtpd[11118]: connect from unknown[88.249.45.76]
    Mar 29 19:23:10 planetsofa postfix/smtpd[11118]: 5F14113E0005: client=unknown[88.249.45.76]
    Mar 29 19:23:10 planetsofa postfix/cleanup[11122]: 5F14113E0005: message-id=

  • You are a life saver.
    I was having an absolute nightmare with Google Apps I needed just one email forwarded on this domain as the old hosting company was shutting up shop, bugs and delays everywhere doing it on Google Apps, support says wait 24 hours, I DON’T HAVE 24 HOURS EMAILS ARE BLACK HOLING!!

    Thanks to you, sorted (for now).
    THANKS

  • Work perfectly, but I just want to report a problem. I configured forwarding email myname@mydomain.com to myname@gmail.com. Then I tested sending mail from myname@gmail.com to myname@mydomain.com, but when I refreshed my inbox I did not receive any mail. It seems that gmail cannot send to and receive from the same email address. Could someone explain me why? Thanks.

    • Having the same issue here. I guess it’s not really an issue, but I’d like to know why this happens.

  • Hi. I forwarded all emails (@something.com) to my gmail account. I have only one question. after forwarding an email will postfix delete any local data related to the email? or it will save the same email on the server too? where is the postfix folder for saving emails? /var/mail/ is always empty for me

    • Yes. I dont want it to store any data in the server.

      Anyone can answer the question?

    • Thanks for your comment.. I was trying it for hours with my own gmail.. forwarding to my own gmail.. could not get it to work…

      Finally scrolled down.. tried from another email account.. also gmail.. and it worked!

      Thanks!

      And also thanks for the tutorial. Its fantastic!

  • Excellent! Thanks!

  • How do I do this from te userspace, I know there is like a ~/.forward file that allows you to choose as a user level where you want your emails to be forwarded.

  • How can I forward all emails sent to an address, to another corresponding address. For example, when I receive the emails sent to “a-user-email@mydomain.com”, I want to forward it to another email with the same username, but different domain, like “a-user-email@myanotherdomain.com”? I just want to change the domain of target email, but not the email name. Because I don’t want to forward to my email only, but my users’ email too.

    • Were you able to figure this one out? I’m looking for the same thing.

  • Hi
    I think I have problems with DNS

    $ dig domain.com mx
    return > “domain.com. 3600 IN MX 10 mail.domain.com.”

    $ dig domain.com a
    return > “domain.com. 3600 IN A 999.999.999.999”
    but it should be > “MAIL.domain.com. 3600 IN A 999.999.999.999”
    correct?

    then create an entry ‘A’ mail pointing to the ip
    $ dig domain.com mx return:

    ;; ANSWER SECTION:
    domain.com. 3600 IN MX 10 mail.domain.com.

    ;; ADDITIONAL SECTION:
    mail.domain.com. 3600 IN A 999.999.999.999

    Is that correct?

    My emails returned with error “DNS Error: Domain name not found”

    This was the best tutorial I found
    Thank you!

    • Your dig query for MX records returned the subdomain of mail.domain.com. Therefore you need to set an A record for this subdomain as well, and not just for the root domain.

  • What is the difference between alias ​​and virtula_file?

    • aliases are for local (username only, no domain) redirects.

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