I am planning to host a test instance of discourse for an NGO I volunteer for on my VPS. It is supposed to accompany an event with around 100-150 participants so I expect some traffic over the weekend of the event. The only unanswered question I currently have is the mail setup. I considered self-hosting the SMTP relay myself but found a lot of recommendations to rather outsource it to an external service. I have thus been wondering if there are recommendations for an SMTP relay service? GDPR compliance on a European server is a must. Ideally, it would be inexpensive, easy to cancel, or even free as I am planning to take the instance down after the event and learn from the experiences and comments of the users.

Any ideas or recommendations? Thanks in advance!