@ryantownsend Back when email was new and unfamiliar, you didn't choose. You just got given a mailbox by your university (which you would use as you're personal address, even if technically it wasn't), or your ISP.
By the time that independent email providers were really taking off, you had clear, concrete reasons for your choice, such as price (Hotmail), brand recognition (Yahoo!), or features (GMail). But Mastodon servers all look kind-of the same, so how do you select one?
@mavit go with a big generic one (e.g. mastodon.social) or, if you want to identify as part of a community, search for the most appropriate and (if you care to) read over their moderation policies that are publicly visible. Done.