Original message:                                      To: bill@irs.gov                   Hi.                   qmail-inject    Fill in the complete envelope and header:                        |             (envelope) from joe@heaven.af.mil to bill@irs.gov     |             From: joe@heaven.af.mil     |             To: bill@irs.gov     |                  |             Hi.     V                                qmail-queue     Store message safely on disk.                Trigger qmail-send.     |                  V                                qmail-send      Look at envelope recipient, bill@irs.gov.     |          Is irs.gov in locals? No.     |          Is bill@irs.gov in virtualdomains? No.     |          Is irs.gov in virtualdomains? No.     |          Is .gov in virtualdomains? No.     |          Deliver remotely to bill@irs.gov.     V                             qmail-rspawn    Run qmail-remote.     |                  V             qmail-remote    Look at host name, irs.gov.                Is irs.gov listed in smtproutes? Yes: ":bigbang.af.mil".                Look up DNS A for bigbang.af.mil and connect by SMTP:                                      MAIL FROM:<joe@heaven.af.mil>                   RCPT TO:<bill@irs.gov>