How do instances that use platforms such as Lemmy send verification, password reset, etc. e-mails? Do they use SMTP or some external service that provides an API?
Either a local SMTP server (less used) or an external service (more common). The SMTP is configurable but I believe most used option is ssl smtp over port 587.
theyre routing through a standard SMTP service either hosted by their ISP or an external service theyve sighed up for to relay their mail.
i push mine out through AWS SMTP service, for example.
@Asudox my mastodon connects with smtp to a locally running sendmail which then forwards the messages signed with dkim
Is running a SMTP server a pain in the ass? Like hard to maintain?
Yes, it is.
I've been running my own mail server for decades now (a quite odd hobby, I know) and that's not to be recommended for anyone who doesn't have a particular interest in e-mail. SMTP is from the early 1980s with roots in the 1970s and has had layer upon layer bolted on since then. It's a fantastic mess.
I'll counter the other comments. It's not any more difficult to maintain than any other service. What is a pain is the spam, and as I run it for a business the users. The biggest problem I have is other mail servers been incorrectly configured for SPF, DKIM and dmarc , usually it's things like external billing platforms that have been integrated incorrectly by customers and suppliers. Spam is now starting to come though with all the proper headers for SPF and DKIM
I self host a lot of services, but I will never self host my email server If any of my self hosted service would have to go down, I will work on it as soon as I can, but it coudl that it's not that soon. If I would have self hosted my own email server at it would go down, I would have to work on it straight away because usually after 24/48 hours the other email server give up and send back the email (that was directed to me) to the sender, I could not receive airplane ticket for example and a lot of other stuff. What if that would happen when I'm on holiday in the other side of the world??? 🙈
@Asudox once I set it up correctly I didn't have problems yet
But big email providers like google like to not deliver emails if you do stuff wrong. I'm not self-hosting for my personal email stuff, but I didn't want to pay or put my email pw on my server, so I had no choice (i could've created a new email account, but i didn't want to put a 3rd party in the middle)
Yep Lemmy uses SMTP and in my experience most self-hostable platforms do as well. You can see in the Lemmy config documents how it gets set up: https://join-lemmy.org/docs/administration/configuration.html.