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When fetching large documents via SSL, the imaplib 
attempts to read it all in one chunk, but the SSL 
socket layer only returns ~16k at a time.
The result is that Python will end up allocating, say, 
a 15 megabyte block, shrink it to a few kilobytes, 
occasionally allocate a medium-sized block (to hold 
the list of chunks), and repeat this again and again 
and again. Not all malloc implementations can reuse 
the (15 megabytes minus a few kilobyte) block when 
allocating the next 15 megabyte block. In a worst 
case scenario, you'll need some 13 gigabytes of 
virtual memory to read a 15 megabyte message...
A simple solution is to change
 data = self.sslobj.read(size-read)
to
 data = self.sslobj.read(min(size-read, 16384))
For more on this, see this thread:
http://groups.google.com/group/comp.lang.python/browse_
frm/thread/3737500bac287575/d715bf614a86e786
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