Fix for Postfix mail issue after upgrading from OS X 10.6 to 10.7

Postfix stops working. It throws errors like:

Jan 13 12:18:52 huggybunny postfix/master[2254]: warning: process /usr/libexec/postfix/smtp pid 2299 exit status 1
Jan 13 12:18:52 huggybunny postfix/master[2254]: warning: /usr/libexec/postfix/smtp: bad command startup -- throttling

I had it set up to replay through GMail. Looks like the /etc/postfix/sasl_password file was deleted during the upgrade. All I had to do was create it again per these instructions, reload postfix and it was good to go.