A message for all people who sent me an email today which bounced back:

I just noticed that I didn’t get any emails today. So I looked up my server settings and the status and everything seemed fine, but in reality the imap-daemon had crashed, without the monitoring service noticing it, argh! So it could be that some emails, especially addressed not directly to my address, but to an old one, have bounced. If it was something important please feel free to resend your mail as everything is back to normal now. Thanks and sorry for any inconvenience!