Hosting your own mail server for example is probably not worth it for most people.

If the homelab involves using an IP address under a residential internet service, that quickly goes from "not worth it" to "literally impossible".

Unless you're willing to set it up so SMTP and IMAP are tunneled through a VPS that you also pay for, the story becomes:

Why can't I receive my test mail?
Oh, the ISP blocks inbound SMTP connections.

Why can't I access my mailbox from outside my home?
Oh, they also block IMAP and POP.

Why do my outgoing emails all end up in the spam folder?
Oh, most email providers insta-spam anything from residential IPs ranges.

And then, even if it's not a homelab, DIY email hosting is:

Oh my god, there's so much spam.
I need to set up more aggressive filters.

Why did this important email get filtered?
Oh, I need to make the spam filter less aggressive.

Why are my outbound emails being marked as spam?
Oh, I need to set up DKIM and SPF.

Why is it still being marked as spam?
Wait, some providers require reverse lookup hostname of the mailserver to match the sender name? Fuck.

Oh, ok, now my server or its IP block got added to a spam list.
How do I get removed from the spam list?
Painfully. Very painfully.

And so on.

It's really not worth it.

Yeah.. I want to host mail, but I loath the idea of hosting my own mail.