[trzczy]

Create system backup for safety first.

Update and upgrade Debian.

Code:

apt-get update apt-get upgrade

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It may last more then 10 minutes.
The advantage of Debian update and upgrade in my case was that it stopped permission and ownership issues of the exim 4 log path.

Try to send mail. The recipient should be valid. 

Code:

echo "test message" | mail -s "test message" recipient12x3@gmail.com

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root@debian:~# echo "test message" | mail -s "test message" recipient12x3@gmail.com
root@debian:~#

Check exim 4 log file

Code:

cat /var/log/exim4/mainlog

---

root@debian:~# cat /var/log/exim4/mainlog
2016-12-28 08:16:42 exim 4.84_2 daemon started: pid=24997, -q30m, listening for SMTP on [127.0.0.1]:25 [::1]:25
2016-12-28 08:16:42 Start queue run: pid=24998
2016-12-28 08:16:42 1cMDqt-0000Zx-63 ** user@debian <root@debian>: Unrouteable address
2016-12-28 08:16:42 1cME5y-0006VF-OT <= <> R=1cMDqt-0000Zx-63 U=Debian-exim P=local S=4236
2016-12-28 08:16:43 1cME5y-0006VF-OT ** user@debian <root@debian>: Unrouteable address
2016-12-28 08:16:43 1cME5y-0006VF-OT Frozen (delivery error message)
2016-12-28 08:16:43 1cMDqt-0000Zx-63 Completed
2016-12-28 08:16:43 End queue run: pid=24998
root@debian:~# 

As you see in the log something crashed.

To fix it run exim 4 reconfiguration.

Code:

dpkg-reconfigure exim4-config

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Watch the settings and set them accordingly to the screenshots:



















Then get it to work. Put the following commands:

Code:

update-exim4.conf /etc/init.d/exim4 restart

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Resend test mail

Code:

echo "test message" | mail -s "test message" recipient12x3@gmail.com

---

Check exim 4 log file

Code:

cat /var/log/exim4/mainlog

---

2016-12-28 09:51:40 1cMFZs-0000fg-4U <= root@blabla.com U=root P=local S=329
2016-12-28 09:51:40 1cMFZs-0000fg-4U gmail-smtp-in.l.google.com [2a00:1450:4010:c0b::1b] Network is unreachable
2016-12-28 09:51:41 1cMFZs-0000fg-4U => recipient12x3@gmail.com R=dnslookup T=remote_smtp H=gmail-smtp-in.l.google.com [173.194.222.27] X=TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128 DN="C=US,ST=California,L=Mountain View,O=Google Inc,CN=mx.google.com" C="250 2.0.0 OK 1482936701 h26si29181103lji.97 - gsmtp"
2016-12-28 09:51:41 1cMFZs-0000fg-4U Completed

Bravo! This is the log you have been waiting for! You can read the mail in mail client of recipient. Notice that the sender is root <root@blabla.com> in received mail.

[try3vps]

I vote for postfix because I use postfix most of the time.

And not seeing how exim 4 can be used better than postfix. I am just satisfied with using postfix.

Thanks for the tutorial anyway.