I have a raspberry pi running postfix. I Realised unless I open port 25 I absolutely cannot receive emails (I have 587 open and can send but not receive them). However I heard there are scaries online which someone could potentially send emails from your server without consent. I believe as well my ISP doesn’t block port 25. Is there anything I should do right now before opening port 25, or should everything be safe enough?
friends dont let friends host email. its just become too top heavy (complexity-wise) if you want it to be fully functional and secure.
Buy your own domain name and put it in front of someone else’s service. This is going to be a ton of work to do correctly and you’re unlikely to be able to host it out of your house.
Also, something you’re running off a Raspberry Pi in your house is not going to meet most definitions of ‘reliable’.