Hi @sandronicolasm,

First I would like to apologize if some of my answers do not correspond with your questions however I believe we don’t have anyone that speaks Spanish to directly help you, so I’m using Google Translate.

1. What I understand from your question is you wish to have a proper FQDN for your droplet. You’ll need to use an actual registered domain otherwise nobody else would be able to access it.

2.Yes, Postfi is a pretty good mailing service. I’ll recommend using it as it’s the mostly used one.

1. The best mailing client for me would be either outlook or thunderbird. Both come with pretty cool functionalities and it’s actually up to personal preference.

Regards,
KDSys