What error message do you get?

Thanks. There was no error message for the downloading of messages. In the error log I found later a comment that the certificate is already existing and that a new one should be requested. For sending messages the error message said to check the SMTP settings. These were according to my service provider correct. I have a found a solution by creating local folders in my old profile, transferring all emails into the local folders and then only copying the local folders into a new profile. This works now. I just have all older mails in separate folders, which to me is not a problem.