After days of trying to request some help on postfix dovecot setup
reddit / selfhosted

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azadiho · 2023-12-30 08:16

Hey,

So I was able to setup a postfix and dovecot server with all the
proper configuration to send and receive email within the server, just
have not had any luck figuring out how to connect to the server using
smtp outside the network.

For referene, I followed line by line of this guide

[https://hetmanrecovery.com/recovery\_news/how-to-install-and-
configure-postfix-mail-server-with-dovecot-on-linux-
ubuntu.htm](https://hetmanrecovery.com/recovery_news/how-to-install-
and-configure-postfix-mail-server-with-dovecot-on-linux-ubuntu.htm)

Is this guide missing something that I should not of in order to use
smtp to connect to the server?

Greatly appreciate any help

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redhatnation · 2023-12-30 08:29

If you're testing from a home ISP, it's possible your ISP is blocking
SMTP outbound connections.  (this is a wild guess that might not apply
to you)


If you have a server outside your home network, try testing from
there.  Also, some hosting providers block smtp by default unless you
ask for blocks to be lifting (am thinking of AWS)

If you want, I'd be happy to test from one of my mailservers.  Send me
a DM with the domain name and I'll run a quick test.  You can also
test using various online tools like mxtoolbox.com.

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azadiho · 2023-12-30 08:31

I used multiple online smtp checkers online, also I am using ionos for
the vps they unblocked port 25 for me

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redhatnation · 2023-12-30 08:35

Other things to check w/postfix:

in [main.cf](https://main.cf):

Verify inet\_interfaces = all

Otherwise, postfix might only be listening to localhost connections.

This is good:

\[root@dns1 \~/postfix-dir\]# sockstat -4l
root     master     1073  13 tcp4   \*:25                  \*:\*


This is localhost:

root    master   932   23 tcp4   127.0.0.1:25        \*:\*

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redhatnation · 2023-12-30 08:38

Ok, last thing then I'll hush.  Try to telnet to your mailserver on
port 25  and see if you get an HELO or EHLO:

telnet mailserver.domain 25

or

telnet -6 [mailserver.com](https://mailserver.com) 25

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redhatnation · 2023-12-30 08:49

I can't speak about ionos (not familiar with them)


Any firewalls on your mail servers?  That you're getting timeouts
suggests, maybe, that something is squatting on your SMTP connection
attempts.  Even when AWS removed SMTP blocks for my mailservers, I
still had the random provider who flat out refused to talk to AWS IP
blocks.

Can you verify postfix is listening on port 25?  For FreeBSD, I use:

\~/postfix-dir\]# sockstat -4l | grep 25
root     master     1073  13 tcp4   \*:25

and ipv6:

\~/postfix-dir\]# sockstat -6l
USER     COMMAND    PID   FD PROTO  LOCAL ADDRESS         FOREIGN
ADDRESS
root     master     1073  14 tcp6   \*:25

On Linux servers, replace sockstat with ss:

\~$ ss -4l | grep smtp
tcp   LISTEN 0      100        \*:smtp        0.0.0.0:\*
\~$ ss -6l | grep smtp
tcp   LISTEN 0      100            \*:smtp           \[::\]:\*

The offer is there if you want me to test from one of my mailservers.
I can send you the IP I'd use if that would help.