[arch-general] Which MTA to use to store mails?

Hello, topic is probably not so precise. What I want is the following: - I've got some Email/IMAP account. - My mail is hosted on a server by GMX. - I've got too many Emails on the host. - I don't want to loose any of the emails. - So I will have to install my own mail server, fetching all my emails from the host. - The mail server will then have to interact with my providers server like a client, working as a server for me. I'm sure there're some good servers, but I don't know which one - works as expected, - and is easy to configure. Any help appreciated. Kind regards Peter