Enable Procmail large file support

In most distro, Procmail does not support large file by default,
If your mailbox file larger then 2G, you may see maillog like
(can't create user output file. Command output: procmail: Couldn't create "/var/spool/mail/user" )
You have to recompile Procmail using
make CFLAGS='-D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE'
then Procmail can handle mailbox file larger then 2G.