ok, I found out, I have to login with my email account, which I previously created in ISPC webinterface email> email mailboxes.
But how can I send SMTP php mail () if i donīt have my domain under my mail server, but under google apps. I canīt just create
smtpsender@mydomain.com because its under google apps. Now Iīm address of another domain hosten on my server.