[Dovecot] possible nfs issue

[Cor Bosman]

Hi all, we've started receiving complaints from users that seemingly use more quota than they actually have. We noticed that these users have (in some cases many) .nfs files in their mailspool. Some of our admins checked their own dirs, and noticed them there as well.  This could of course be unrelated to dovecot (kernel issue, netapp issue) but maybe somehow has an idea about if dovecot could cause this. This has been going on for at least a year, not really enough to notice before now. 

root at userimap1# find . -type f|grep -i .nfs
./cur/.nfs00000000003967ad003c0603
./cur/.nfs000000000757b44b003be609
./cur/.nfs00000000035e89bd003be60b
./cur/.nfs000000000796251c003be60c
./cur/.nfs000000000796251f003be60e
./cur/.nfs000000000262f9a1003be33a
./cur/.nfs00000000096513f3003be524
./cur/.nfs0000000007962525003be60f
./cur/.nfs0000000003e7d8ab003be62b
./cur/.nfs00000000026f4fad003be50d
./cur/.nfs0000000000bdaeab003c0611
./cur/.nfs0000000005da42c7003be525
./cur/.nfs0000000003d74729003be526
./cur/.nfs000000000229769e003be535
./cur/.nfs000000000440969e003be516

With NFS these files are created when a file gets unlinked, but another process still has it open. It disappears as soon as the other process closes it. For some reason they dont disappear. As far as I can tell we've had no server crashes that could explain this.  One possible theory is that a rename happens after an unlink. In that case the file remains. This could possibly be a dovecot issue. 

Anyone else with NFS mailspools seeing this?

Cor