Setting up mail alerts on Proxmox

This guide is assuming you’re using gmail because it is the most common/popular, but you can use whatever (I use sapo.pt for example).

Based on this video by Techno Tim

Install dependencies

apt install libsasl2-modules mailutils

Save creadentials

Note that you might need to use an app password if you have 2FA enabled.

echo "smtp.gmail.com:587 example@gmail.com:password" >/etc/postfix/sasl_passwd
chmod 600 /etc/postfix/sasl_passwd

Generate db file

This encodes the password in the file.

postmap hash:/etc/postfix/sasl_passwd

Configure postfix

Comment the relayhost= line and append the following to /etc/postfix/main.cf (adapt to your needs):

relayhost = smtp.gmail.com:587
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_security_options =
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/ssl/certs/Entrust_Root_Certification_Authority.pem
smtp_tls_session_cache_database = btree:/var/lib/postfix/smtp_tls_session_cache
smtp_tls_session_cache_timeout = 3600s

Then reload postfix’s config:

postfix reload

Test it

echo "This is a test message sent from postfix on my Proxmox Server" | mail -s "Test Email from Proxmox" your-email@gmail.com

Configure the “from” name (optional)

Install postfix-pcre dependency:

apt install postfix-pcre

Add the following to /etc/postfix/smtp_header_checks (adapt to your needs):

/^From:.*/ REPLACE From: Proxmox <example@gmail.com>

Call postmap on the file:

postmap hash:/etc/postfix/smtp_header_checks

Append the following to /etc/postfix/main.cf and reload postfix’s config:

smtp_header_checks = pcre:/etc/postfix/smtp_header_checks

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