[MlMt] unintentionally clicked-away notice about items in exchange account

[Lars Ippich]

Usually on every start of MailMate I get this nagging notice about some 
e-mails that are not really e-mails, because I have set up an exchange 
account and while I have un-subscribed most exchange folders, there are 
some items in the Trash for instance that don't behave like normal 
e-mails.

And that notice is fine, I always choose to temporarily ignore those 
specific messages (and think to myself I can procrastinate actually 
getting rid of them to fix the root of the issue for at least until the 
next start of MailMate ;) ).

Today, however, I was writing in another application while I had 
MailMate start and then this annoying thing happened where a new notice 
pops up and at the same time you're typing a text that contains spaces 
... so I accidentally hit the space bar on whatever the default option 
is in that notice window. I have no idea what I have actually hit, but 
it wasn't the "Temporarily ignore those messages" button for sure. How 
do I get the window back? Any place to reset that notice?