gather all the messages from two different servers

[Soporte247]

I have a domain I used a vps and after a while movement and started using it on another server, now I have emails stored on the old server and the new need to gather all previous post, what alternatives I have to move all messages a single server without damage the messages?

[canobi]

Use a desktop client like Thunderbird - configure accounts for both servers and copy/paste the messages from old server's folders to the new one.