[Dovecot] returned error 83 (Out of memory)

[J Contad]

Hello!

I've setup dovecot a few months ago, and it was working pretty swimmingly.
Then, out of nowhere, we started getting this error:

Apr 21 19:15:17 IMAP(xx at xxx.com): Fatal: block_alloc(1073741824): Out of
memory
Apr 21 19:15:17 IMAP(xx at xxx.com): Error: Raw backtrace: imap [0x49e5e0] ->
imap [0x49e643] -> imap [0x49dba1] -> imap [0x4a7f6d] -> imap [0x4a7f98] ->
imap [0x4a8028] -> imap [0x49bf6f] -> imap(buffer_write+0xe4) [0x49c334] ->
imap(mail_cache_lookup_headers+0x146) [0x46dcf6] -> imap [0x458162] ->
imap(index_mail_get_first_header+0x45) [0x458685] -> imap [0x45fe44] -> imap
[0x460008] -> imap [0x4796d1] -> imap(hash2_lookup+0x64) [0x4a1c94] ->
imap(mail_index_strmap_view_sync_add+0x85) [0x47ab05] ->
imap(mail_thread_init+0x2a5) [0x4602f5] -> imap(cmd_thread+0x161) [0x41f931]
-> imap(cmd_uid+0x78) [0x41fb38] -> imap [0x42079c] -> imap [0x420852] ->
imap(client_handle_input+0x3f) [0x42098f] -> imap(client_input+0x5f)
[0x4214df] -> imap(io_loop_handler_run+0xf8) [0x4a63a8] ->
imap(io_loop_run+0x1d) [0x4a54ed] -> imap(main+0x620) [0x428db0] ->
/lib64/libc.so.6(__libc_start_main+0xf4) [0x3f75e1d8a4] -> imap [0x419969]
Apr 21 19:15:17 dovecot: Error: child 25918 (imap) returned error 83 (Out of
memory - see mail_process_size setting)

The folder (which is shared) has about 8 thousand emails in it. I'm not sure
if it's pertinent, but the dovecot.index.cache file is about 8MB.

Help?

Cheers,
-- 

John