smtp problem

[huber]

strange smtp behavior :

doing the smtp-stuff by hand i get the following output :

telnet mailserver.xxx.com 25
Versuch...
Verbunden mit .........
Escape-Zeichen ist '^]'.
220 mailserver.xxx.com ESMTP
auth login
334 VXNlcm5hbWU6
userid_base64
334 UGFzc3dvcmQ6
passwd_base64
235 ok, go ahead (#2.0.0)

put doing the same with python ( set_debuglevel(1) ) i get an error :

send: 'auth login\r\n'
reply: '334 VXNlcm5hbWU6\r\n'
reply: retcode (334); Msg: VXNlcm5hbWU6
send: 'userid_base64\n\r\n'
reply: '334 UGFzc3dvcmQ6\r\n'
reply: retcode (334); Msg: UGFzc3dvcmQ6
send: 'passwd_base64\n\r\n'
reply: '501 malformed auth input (#5.5.4)\r\n'

does someone know what's going wrong ?

thanks
udo