@JackJohansson yes, and everything i learnt lead me to the conclusion that it was a horrible mistake that took a lot of time and effort for super minimal gains

it's a significant amount of work, and poorly documented

there's a reason people pay other people for it, and all I was trying to do was forward email on to GMail and provide an SMTP

getting TLS, DPKIF etc, all set up was a pain, and without it it would mean half my mail would be flagged as spam or my emails wouldn't arrive

and after months trying to get it working right, I still had an issue where when sending an email it would show up in my inbox as if i was the recipient too

some things just never worked quite right either, in the end a £2 pm Google Apps payment sorted it all out overnight

and you can't just set up a mail server either, you have to maintain it, it's an ongoing support thing

and of course the worst case scenario is much worse if you're self hosting mail

so unless you're planning on doing it regularly, and really delve into the research, and you're doing it for an employer fulltime, don't do it. Read up about it sure, learning is fun, but don't self-inflict pain

@TomJNowell Thanks for both explaining and scaring me off :P I finally figured it out though, problem with SSL. The reason is that I needed to setup multiple email accounts from multiple domains (maybe a total of 20 accounts), so gmail and other solutions were not viable.

why not? I have all my domains piping into the same account, and the option to have separate accounts is doable

It wasn't my decision though, the employer was insisting on moving everything into a single dedicated server.

It was really annoying to set it up, specially without any control panel or interface, and specially for a windows user

I hope you charged extra for the setup time?

In those situations it's always an option to simply say that isn't a service you provide

eh they pay me monthly so it's their time that is wasted

one final creepy question. I've seen that some people say you should set the /etc/hosts file like this: extrenal-server-ip hostname.tld, and some say it should be like 127.0.0.1 hostname.tld. Which one is a better approach?