If you get this error you may assume it is a lack of memory, which it could be, but more likely it is the default memory size of 256M. The file in this example was about 350M big which of course exceeds the virtual memory limits. This makes sense in smaller mail servers but if you have large amounts of users or e-mails this limit should be bumped. Check your default size limit: doveconf -n | grep -E 'vsz_limit|service imap' default_vsz_limi........

This server was experiencing loads of up to 80 and maxing out the RAM and kmemsize on a CPanel VPS. There were literally dozens if not hundreds of exim processes. I have no idea why exim has such a design that would allow it to consume this much CPU and RAM. Any normal MTA should not be spawning so many processes, it should be processing them in sequence and if it is going to spawn hundreds of processes in response to a large volume of mail, it's better to have a delayed del........