It looks like an error may have been introduced during the editing of the
"Use Postfix" article.
I think the values used in password_maps file and the main.cf file need to
match. Otherwise "WantAuthError" shows up in the logs:
Aug 03 12:12:57
eb2027-01.cs.siue.edu postfix/smtp[8960]: 11DFB19523: to=<
gregory.lee.bartholomew(a)gmail.com>, relay=smtp.gmail.com[74.125.69.109]:587,
delay=0.39, delays=0.03/0.04/0.3/0.02, dsn=5.5.1, status=bounced (host
smtp.gmail.com[74.125.69.109] said: 530-5.5.1 Authentication Required.
Learn more at 530 5.5.1
https://support.google.com/mail/?p=WantAuthError
f17sm75891337ioc.2 - gsmtp (in reply to MAIL FROM command))
I had used "[smtp.gmail.com]:587" in both places because
smtp.gmail.com is
an SMTP server, not a domain name against which an MX query should be run.
From the man page:
$ man postconf.5 | grep -A 19 ^relayhost
relayhost (default: empty)
The next-hop destination of non-local mail; overrides non-local
domains in recipient addresses. This information is overruled with
relay_transport, sender_dependent_default_transport_maps,
default_transport, sender_dependent_relayhost_maps and with the
transport(5)
table.
On an intranet, specify the organizational domain name. If your
internal DNS uses no MX records, specify the name of the intranet gate‐
way host instead.
In the case of SMTP, specify a domain name, hostname,
hostname:port, [hostname]:port, [hostaddress] or [hostaddress]:port. The
form
[hostname] turns off MX lookups.
If you're connected via UUCP, see the UUCP_README file for useful
information.
Examples:
relayhost = $mydomain
relayhost = [
gateway.example.com]
relayhost = uucphost
relayhost = [an.ip.add.ress]
Also, the Wikipedia page on MX records points out some limitations with the
MX protocol:
"The MX mechanism does not grant the ability to provide mail service on
alternative port numbers <
https://en.wikipedia.org/wiki/Port_number>, nor
does it provide the ability to distribute mail delivery across a set of
unequal-priority mail servers by assigning a weighting value to each one." (
https://en.wikipedia.org/wiki/MX_record)
So, I think "[smtp.gmail.com]:587" is the proper value. I think other/newer
tricks are used to load balance the
smtp.gmail.com DNS name and route
traffic to the nearest/best server and MX lookups should be avoided in this
case. I could be wrong though. I'm not an expert in this field.
gb