Using UID with gaps

[domiller]

I am trying to read all the messages in a *large* gmail account.  I quickly discovered that I needed to break it into chunks so that my system is not overloaded.  It seemed that uid= with max= was the proper way to do that, and it almost works.  I picked 200 as a viable chunk size.

 

It seems that a combination of UID={some number} and max=200 does not retrieve the next 200 messages, but the next 200 UIDs.  If a large number of messages have been deleted, there may be a gap in the UIDs of greater than 200, at which point the call returns zero messages.

 

Finally to my question... is there some way to reasonably determine the higest UID in use?  That way if my call returns zero I can see if I have reached the end and, if not, increment the UID by 200 and try again.  Otherwise, I have to assume that I have reached the end of the mailbox. This is frustrating when I really haven't.