SMTP Providers

Does anyone have any prefered SMTP providers to use with my Mobilizon instance?

I’ve looked at AWS but they’re asking about the patterns in which this application sends email. Does this software tend to send a ton of reach outs for suggested events, or is it purely transactional (user’s events that they RSVPed to?)

Emails are mostly transactional. Users may get emails to inform them from events organized by groups they follow, or activity in the group, but both are opt-in.