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?
If you manage to get a good SMTP relay host or authenticated SMTP account for your outgoing email then playing around with small scale self hosting email (Granted that it is not your important daily driver email accounts) can be an interesting and fun experience. But you will have to invest some time reading and tweaking and figuring things out. Slightly comparable with installing Arch Linux. Lots of people will warn you to not do it but you might learn a few valuable things on the way there.