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’.
IMHO a RasPi is just not reliable enough. Your internet connection is just not reliable enough. You are going to lose some of your incoming mail and NOT notice it, unless you have somebody who hosts a secondary MX for your domain.
Chances are also that it’s not powerful enough when some of these automated attacks come knocking.
You should be aware that a large number of mail hosters will block all mail from your server merely because it is sent from a dynamic IP address.
The domain won’t change that. Even with a static IP if it’s coming from an ISP owned up block you’re likely going to get banned. Even with reputable VPS’ it’s hard. Make sure you have DMARC, DKIM, and SPF setup, but even then almost certainly going to get banned. The big player are creating and inherent monopoly instead of improving their spam filters.
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.
Ideally, don’t. Self-hosting email is complicated, easy to get wrong (and dangerously wrong, where people could use your server as an open relay and send spam).
That said, if you really want to, make sure you’re not accepting email except for what’s destined for you. There are a bunch of postfix best-practice guides out there that can be easily found with a Google search. I don’t host my own email, so I can’t vouch for any.
Agreed. I used to host email professionally and would not recommend managing your own mail server. It will constantly be under attack by spammers and if the inbox email address is exposed at all, soon 90% of incoming mail will be spam and you’ll need antispam software to filter it.
Not sure about you latter point tbh. I run an email server, with nothing but grey listing and spamassassin and the amount of spam is absolutely minimal.
Proper config and fail2ban easily takes care of direct attacks.
Nevertheless, I wouldn’t recommend it to anyone but the most determined.
If you follow the ISPMail guide at https://workaround.org/ you’ll be safe.
I heard there are scaries online which someone could potentially send emails from your server without consent
That’s called an open relay and websites like https://mxtoolbox.com/diagnostic.aspx can test for it.
Either way your biggest issue won’t be that, if you’re running on a residential internet connection the IP is already flagged as such and will have a very low reputation with other e-mail providers causing Microsoft, Google and any other large provider will simply refuse your email. You’ll also need reverse DNS for your IP pointing at the domain you’re using that your ISP is most likely not going to provide.
