postfix, sasl and some upper case letters...

So I was trying to figure out why i kept getting this error:

postfix/smtpd[PID]: warning: : SASL PLAIN authentication failed: generic failure

Took me a while but then i found out the problem was really simple .. - sort of annoying really ;)
The solution was in /etc/sasl2/smtpd.conf: I had this:

mech_list: PLAIN

The solution was actually just changing one line:

mech_list: plain

so it was just that I wrote PLAIN instead of plain .. who would've thought of that at first..
Hope this helps someone else maybe - or me next time i do this and forget what it whas ;)