cyrus Imapd deliver -e, what does the -e?

Question

I asked myself what the -e Option in the Cyrus program deliver does. E.G. the -e is used in the postfix Configuration in master.cf, but I cannot find any reference to a -e option in the manpages of deliver.

Does anyone know what this option exactly does?

Heres a master.cf line from postfix. Alle other Options are clear to me except the -e

cyrus       unix  -       n       n       -       -       pipe    flags=R
  user=cyrus      argv=/usr/sbin/cyrdeliver -e -r ${sender} -m ${extension} ${user}

I know using lmtp is far better than cyrus deliver, I only used this as an example.

Answer 1

Apparently it does nothing.

The source of deliver.c from cyrus-imap 2.1.18 includes this in option handling:

    case 'e':
        /* duplicate delivery. ignore */
        break;