Thunderbird sync time? (reverse quota warning)

[E.B.]

For reverse quota warning, it looks like webmail works nice.

quota_warning3 = -storage=100%% quota-warning below %u # user is no longer over quota

But using thunderbird I deleted enough messages to go below
quota and I deleted them from trash folder too. But mail log
does not show thunderbird connecting to imap to actually
delete mails and get the trigger below quota warning msg.

It's i thinks a thundrbrd behavior but i wonder if anyone on 
this list knows how it works? Do i just keep waiting for it
to sync eventually? or???????

TIA!