Resolved Mails not working - Plesk server, domain hosted in other registrar

[badkamermateriaal]

Hello,

We have recently moved to a plesk managed hosting with ionos and have serious problem with emails.

our domain: badkamermateriaal.nl, hosted with rootnet (outside of ionos)
our hosting: ionos Cloud Server XL with plesk
OS Debian 10.9
Product Plesk Obsidian
Version 18.0.35 Update #1, last updated on May 13, 2021 06:55 PM

The problem:
webiste seems to be working fine.
The emails are not working.

I can log in to webmail and see migrated emails. However if I send messages from there and to those mailboxes, they don't get through.
I also cannot log in to thunderbird - "Unable to connect, connection timed out or This site can’t be reached"

Seems like the mailboxes cannot be accessed from the internet.
I've went through troubleshooting in this article: Incoming/outgoing emails cannot be sent/delivered, but mail service is configured properly

and there is a problem with iptables -L -n | egrep '25|110|143|465|993|995' command,
all records appear like that:

REJECT all -- 167.172.142.125 0.0.0.0/0 reject-with icmp-port-unreachable

Registrar also reported that SRV records are incorrect and they can't add them.

_pop3s._tcp.badkamermateriaal.nl. SRV badkamermateriaal.nl.
_imaps._tcp.badkamermateriaal.nl. SRV badkamermateriaal.nl.
_smtps._tcp.badkamermateriaal.nl. SRV badkamermateriaal.nl.

what do I need to do in order to make emails work? How do those SRV records should look like?
Kind regards

 

[Kaspar]

If I am not mistaken ionos blocks port 25 (needed for email) by default. You Should contact ionos support for help on this issue.

Creating a Firewall Policy - IONOS Help

In this article, we

www.ionos.com

 

[badkamermateriaal]

Many thanks for your help.

We have added SRV records to external domain provider and unlocked VPS mail ports and looks like everything started to work.

Hope that helps someone in the future.