How to send mail over our mail server from hosts outside D-PHYS/ETH?
If you're outside D-PHYS or connected to ETH via wireless networks or VPN and want to send mail over our mail servers, there may be some obstacles depending on the environment you're sending from.
In most cases the configuration as provided in our READMEs should also work outside ETH.
As described in the READMEs, you should have SMTP Authentification (SMTP AUTH) enabled, otherwise you won't be able to send mail to other destinations than the physics department that way.
Be sure to have some encryption (TLS or SSL) enabled to secure your password against sniffing.
Sending mail from host behind firewalls blocking port 25
If you need to send mail from hosts behind a firewall which is blocking port 25 outwards, you can use the SMTPS (SMTP over SSL) port 465 instead. If that doesn't work either, try the submission port 587 instead of 25 and enable TLS and SMTP AUTH.
We use Greylisting to check if sending mail servers are no spam firehose which --- contrary to the standards --- only tries sending mails once. If you have to send mails without waiting for a second try, you must use SMTP Authentification (SMTP AUTH) as recommended in our READMEs