BUG? File descriptor use in cmd_append (for MULTIAPPEND) results in many open files

[Nik Conwell]

I'm using the UW mailutil to transfer mailboxes from UW to Cyrus  
(2.3.7).  It uses APPEND, specifically multiappend (single APPEND  
with multiple messages being appended).  Cyrus-imapd handles this  
multiappend by creating stage files for each appended message and  
leaving the file descriptor open.  The problem is that after 240  
messages, we run out of file descriptors and so an open() of the next  
stage file fails with EMFILE.  I updated /etc/cyrus.conf to make the  
max fds be 1024 (AFAICT kernel MAX) which helped somewhat but not for  
larger mailboxes with > 1008 messages.

Shouldn't the multiappend/append be closing the FD for each stage  
file and then reopening it later as it needs it?

Do people just tweak their kernels to have some insane number of FDs  
available in order to compensate for this?

Or, do people not use mailutil and instead use something that issues  
multiple append commands rather than a single append with multiple e- 
mails?

-nik