qmail-smtpd Receive message by SMTP from another host: | MAIL FROM: | RCPT TO: | | Is $RELAYCLIENT set? Yes: "". | Accept RCPT. 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? No. Look up DNS MX/A for irs.gov and connect to it by SMTP: MAIL FROM: RCPT TO: