Elm creates a lock file everytime it access the mailbox.
When you restored your mailbox from your backup, it also
restored the lock files that was present during your backup
window.

rm /var/mail/{useraccount}.lock

: Our /var/filesystem was inadvertently deleted a while ago, we have
: managed to recover everything,but our elm mail is not functioning
: as it was. We are getting the message "Waiting to read mailbox while
: mail is being received." It then "gives up after 7 iterations".
: Any suggestions?