Just wonder what if my mail server went offline for some periods, and the sending party couldn’t deliver.
Will there be any consequences except I don’t get the mail? I tried searching but they all in the perspective of a sender and get a bounce, rather the other way around.
Some things to consider:
- It is typical for mail servers to retry a couple of times for maybe a day or two. The exact values can differ a lot.
- After this time, the message bounces and the sender (sometimes) gets notified.
- This bounce might get your address removed from newsletters.
So noting substantial other than I don’t get the mail and might get kick out of newsletters?
Correct. But at least for me, even the low risk of some e-mails getting lost is pretty substantial.
SMTP is designed with queues and retries
Unless something has changed massively since I was deeply involved with this stuff, the people that sent you email may get a notification after some hours that their message is being delayed, and maybe after like 24-48 hours they might get a bounce. But if it’s just your SMTP server going down for an hour or two every now and then, the system should be able handle that seamlessly (barring some hiccups like messages showing up with timestamps hours in the past which sometimes is confusing).
What if longer? 6 to 8 hours per day?
The problem with this is the probability of your server being available for the next retry is fairly low.
Usually some sort of exponential backoff is used so it might retry after 5 minutes, 15 minutes, an hour, 3 hours, 6 hours, 24 hours, 48 hours, give up.
6-8 hours is probably too much for anything serious where you don’t want emails to just drop. It will work so if you’re just using it to sign up to sites and stuff, you can make sure your server is on to receive the verification emails and stuff. But I wouldn’t use it for anything important.
Don’t self host email
No need to be that maximalist. Don’t self host email on a desktop machine you turn off.
No, don’t self host email. There are so many things that can go wrong and it will be constantly attacked
Sounds like you had an awful experience about self-hosting email. Want to share with this community so everyone learns?
I’ve been self-hosting Postfix for several years and it’s not difficult, if you’re absolutely confident what you do. I don’t recommend it if you don’t know basic behaviors and internals of SMTP and relaying. Also you need to know how to secure your server so you don’t get spammed a lot and getting hammered with brute force attacks.
From time to time you need to react to delivery problems. Most interesting one is perhaps Microsoft, which you need to ask to whitelist your server or your email won’t be accepted.