[Mediawiki-l] Error sending mail: mail() [function.mail]: SMTP server response: 501 Protocol requies only one recipient at a time

[Paul Sanderson]

On top of previous problem I get the following error after an upgrade
from 1.5.6 to 1.7.1 when a user tries to send a new password to
themselves

Error sending mail: mail() [function.mail]: SMTP server response: 501
Protocol requies only one recipient at a time

Can anyone please shed some light on this