Mail server: IP address verification?

[CRBear]

Hello everyone,

Am I correct in understanding that the email server checks from which IP address a connection is established to send an email and by default, it verifies against the Spamhaus blacklist?

I'm asking because we want to send alarm and fault notifications via the Cloudron server from a regular DSL connection, and these addresses or address ranges often appear on blacklists due to dynamic IP addresses.

I'm concerned that important messages from the Cloudron server might be rejected as a result.

Thank you!

[AartJansen]

Depending on where in the world you are, some ISP's offer a static IP. Although there are more considerations like does your ISP block port 25. Or you could have your mail server hosted. ie by linode or hetzner (or others).
Or use a mail delivery service like mailgun.

Also are you sending those notification to email addresses on cloudron, or to mail addresses hosted by other people?

[necrevistonnezr]

If you need to send alarm notifications, i.e. critical messages, use email relay. Reliable deliverability is just not good (impossible to achieve?) from a home ISP connection with a dynamic IP.
There are several threads here on recommended services.

[humptydumpty]

@necrevistonnezr I’m using mailgun and haven’t had any issues at all. Iirc, you have to email them to get placed on the pay as you go plan. It’s basically free unless you go over the send limit.

[girish]

@CRBear said in Mail server: IP address verification?:

Am I correct in understanding that the email server checks from which IP address a connection is established to send an email and by default, it verifies against the Spamhaus blacklist?

The mail server does not make any check for outbound email. The various checks you see in the Email Status tab are purely diagnostic. The idea is if one or more checks are failing there, most likely the email won't be delivered.

The Spamhaus is checked for inbound emails though. The DNSBL zone against which it checks is configurable at https://docs.cloudron.io/email/#dnsbl