Hosting email allows for an easy, and cheap, SMTP server for services that require it. Receiving EMail shouldn't pose an issues. Sending email to users on your own domain shouldn't pose any issues, if for example users are signing up to services like Mastodon using an EMail account on the same Eilean. Sending mail will require TCP port 25 to be unblocked by your network provider, and your IP address to not be blacklisted (e.g. check here).

not managed:

• multiple domains
• multiple servers /load balance