Hello All,
I'm seeing this same problem, however PMG is rejecting the message.
If I email mike@ vs Mike@
the lower case value gets rejected with 554 5.5.1 Error: no valid recipients
for reference the account on the cpanel box is lower case.
I can get it rejected several times, then magically one is accepted.... ( it will get rejected again later )
Not sure if there is a setting to ignore case, or something I may be doing wrong.