M426fdw Outgoing SMTP Profile "The test was unsuccessful. Try again."

[JustinMaxwell]

I cannot get SMTP scan to email working via Google.

With smtp.google.com, the login is refused.  I get an email from Google.  "Sign-in attempt was blocked" 

I cannot enable "Less secure apps" since this is prohibited under our G-Suite configuration.

With aspmx.l.google.com I just get "The test was unsuccessful. Try again." with absolutely no way I can find of learning WHY it failed.

I have even set up Syslog events to a log server, and it gets plenty of messages about printing, but nothing from the email tests. I've enabled Telnet access to the printer but can't see anything useful there either.

I'm trying to scan from a Chromebook or to my email. The HP support site sends me off to a page that describes some 'WebScan" thing, that doesn't appear when I log into the Printers web interface.

I've updated to the latest (20190712) firmware.

Any help or tips on how to see the SMTP conversation, or otherwise get it working or diagnose the problem greatly appreciated.  

NB: There is no Webscan option in the printers Networking→Security→Settings or Networking→Configuration→Advanced

[JustinMaxwell]

Interestingly, the Outgoing Email Profile works(!!!), if I enter the Google Restricted Gmail SMTP server IP address ( 108.177.104.26) rather then it's DNS name (aspmx.l.google.com).

The printers DNS server settings have been pointing at Google (8.8.8.8 & 8.8.4.4) forever, so it's clearly some bug in HPs firmware (what a surprise, not!).  I have confirmed that adding IPv6 DNS resolvers doesn't change anything.

That's four hours of frustration I could have done without.  Hopefully, if this bug is impacting you, you found this thread sooner than that!