[Evolution] "Error occurred while sending" after enabling Google 2-step authentication [with solution]

[Nick Jenkins <nickpj gmail com>]

Hi all,

Ran into a problem this morning, but in the process of writing this
email, I worked out the solution. I'll send this mail anyway, with
solution, so if someone (including myself) encounters the same problem
later on, it's there in the archives.

Some Background: What's happened is that I recently turned on Google
2-step authentication, after reading a horror story of someone having
their gmail password stolen (e.g. from a keylogger on an Internet
terminals), and from that lost their email, contacts, calendars, and
then experiencing bank fraud due to identity theft and reset passwords
on their banking sites, and so forth, and the whole thing sounded like a
total nightmare ... and in the ensuing discussion, the consensus
solution to avoid the same fate was to turn on 2-step authentication,
where you enter a password, plus a numeric code that's SMSed to your
phone or generated on your phone, and only with both of those things can
you log in (i.e. something you know + something you have). So similar to
many banking sites, but you can mark a browser as trusted after the
first successful login, and thereafter you only need your password, so a
bit more convenient.

More background: Most of Google's own apps now support 2-step
authentication, but to help with "legacy" apps that don't support 2-step
authentication, such as Evolution, you can generate an "application
password". This a password that you should use just for that app, and
it's 16 characters of gibberish, so very hard to brute force. It's
supposed to work just like your normal password did previously, without
requiring your phone for authentication, and once you're no longer using
that app, you then revoke the app-specific password, and it no longer
works. If you want further info, it's available at:
http://www.google.com/landing/2step/

Configuration in Evolution: I have this gmail account configured as IMAP
+ for receiving, and SMTP for sending, and previous to this it worked
fine. Also there's a Google calendar configured with the same account.
Evolution version is 3.8.4 

What happened: After enabling 2-step authentication, Evolution prompted
me to enter my password. So I entered the app-specific password I had
generated (once for my email + once for my calendar), and I can view
everything as normal in Evolution, and mark mail as read, and so forth.
The problem is sending mail. Ever since enabling 2-step authentication,
when I reply to mail or create a new mail, and then hit Send, I get a
dialog error box that says:
-----------------------------------------
An error occurred while sending. How do you want to proceed?
The reported error was "Bad authentication response from server.".
[Continue Editing] [Save to Outbox] [Try Again]
-----------------------------------------

Thought process: My suspicion is that Evolution (or gnome-keyring) is
still remembering and using the old password for SMTP sending, rather
than the app-specific SMTP password that it should be using now. Is
there somewhere that I can say "hey, forget that old SMTP password, and
prompt me for the SMTP password next time you need it"?

Solution:
* install "seahorse" (it's in the standard repository of most
distributions), and run it.
* then in the top-right search box type "smtp", press enter
* it should show an entry like this "smtp://youremail%
40gmail.com;auth=PLAIN smtp gmail com:587".
* Right-click on that entry, choose "delete".
* Then quit Evolution, then restart evolution.
* Try sending mail again. This still didn't work, so then I searched in
seahorse for "evolution"
* There were a number of entries named things like "Evolution Data
Source 1220830865 7426 7 redux". You can't really tell what account they
are for by looking at them, but by showing the password for each, I was
able to check if they were the old password, and if so, then delete each
of those entries. I deleted around 6 entries, but I had deleted and
re-added this account a few times in previous years.
* Then quit Evolution, then restart evolution.
* When I tried sending again, it prompted for the password, and I
entered the app-specific password, and then it sent successfully, so
that was the solution.

How Evo could have made this a bit easier to solve:
* Prompting for the password to be entered on encountering a "Bad
authentication response from server." when sending, or allowing it to be
re-entered by clicking a button on that dialog box, would have been
ideal. [this is the first place I looked]  Even a link to open the
relevant Sending Email configuration page could be good, especially if
combined with the entry below:
* Under Edit -> Preferences -> select account -> Edit -> Sending Email,
a way to say "forget password" would have helped. [this was the second
place I looked]

-- All the best,
Nick.