Hello and welcome @Nicca 
Just to add, there’s been a spate of Mailgun [1] Digital Ocean blocking ports as some kind of anti-spam initiative or some such, so you may need to get in touch with them to unblock it if that’s the case.
Though I think changing the smtp port to 2525 could also work as an alternative - re: Email not working on my Discourse site - #10 by pfaffman
