The OOM killer usually kills the process that's using the most memory, which is the reason the system is OOM. Sometimes this can be adjusted. When I'm OOM it's

The OOM killer usually kills the process that's using the most memory, which is the reason the system is OOM. Sometimes this can be adjusted. When I'm OOM it's almost always because some runaway loop used 50GB and it makes no sense to kill any other process. If it's killing your email editor then your email editor is bloated or you just need more RAM - or swap.