I have a postfix server with the following reciptient_restrictions:

smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination

This means if a client wants to send mail from outside our network he has to use authentication. However the clients don't seem to understand this.

Our old qmail server did something (don't ask me what) to make clients temporarily authenticated to send mail from outside our network when they checked their mailbox first, so they did not need to enable authentication for sending mail.

Is there a similar way to allow clients outside our network temporarily to send mail after they have checked their mailbox with postfix/sasl?