[Exim] Maybe a Bug in AUTH LOGIN

Hi,

I'm using exim-4.12 on both Linux and FreeBSD.

It seems that as clients MTAs based on cyrus-sasl library send:

AUTH LOGIN =

instead of:

AUTH LOGIN

( At least the sendmail in RedHat 8.0 behaves so. )

The "=" is treated by exim as $1 that is of zero length, but it should
be ignored so that the user name will be $1 and the password will be $2.

Since the LOGIN mechanism is not officially documented, I wonder should
this problem be of exim's or of cyrus-sasl's? And will the exim developers
be willing to make exim compatible with such "AUTH LOGIN ="?

And when I enabled only LOGIN mechanism, my mozilla-1.2.1 just ignored
it...and it use PLAIN when I enabled both LOGIN and PLAIN... :-(

Best
Regards,

LIU Xin