Fixing the Postfix Envelope Address

I found errors in my /var/log/syslog indicating undelivered email because my MTA didn't recognize the envelope addresses. The Postfix address rewriting readme provided a simple solution: use /etc/postfix/generic to rewrite those "bad" addresses to something acceptable. I did that. But, then I realized that I would need to "build" generic into generic.db (and restart postfix) before I could be sure the rewrites would take effect. A search brought me to a page on Postfix Makefiles; it had more information than I needed, but it did provide the important command. Running sudo postmap generic from /etc/postfix rebuilt my generic.db.