Receiving emails failed (For example by using Hosteurope as Hoster)
Please check if the sender emailaddress really exists! In case of using Hosteurope, you need to set a default emailaddress within the Provider-Backend. You will find this setting in Administration -> Webhosting/Virtual Server Managed -> Skripte -> Standard-E-Mail-Adresse - on this page you're able to select the emailaddress.
Finally you have to set this emailaddress in TYPO3 Installtool:
[MAIL][transport] = sendmail
[MAIL][transport_sendmail_command] = /usr/sbin/sendmail -t -f mail@domain.com
Instead of the mail@domain.com you have to use the default emailaddress, which you had selected in Hosteuropes Provider-Backend. Afterwards the receiving of email should work fine.