1404544 - No DNS record for we-guess.mozilla.org -- Failed EHLO

Status: UNCONFIRMED

(Thunderbird :: Account Manager, defect)

Description

[Clément Février]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:57.0) Gecko/20100101 Firefox/57.0
Build ID: 20170920135025

Steps to reproduce:

Create a new email account.
Enter an email address from a server that rejects invalid host name.
Click on "Continue"


Actual results:

Thunderbird will fail to find StartTLS if provided by the mail server because, if I understand properly, Thunderbird send an EHLO
EHLO we-guess.mozilla.org
450 4.7.1 <we-guess.mozilla.org>: Helo command rejected: Host not found



Expected results:

With a DNS record (we-guess.mozilla.org. IN A 1.2.3.4), EHLO would answer:
250-STARTTLS
and find the correct configuration.

Comment 1

[Andrei Hajdukewycz [:sancus]]

Not sure what this is about, precisely. Is there supposed to be a DNS record for that domain? I've never heard of it before, it's not in prefs, and it seems to be coded into a string in https://dxr.mozilla.org/comm-central/source/mail/components/accountcreation/content/guessConfig.js?q=we-guess.mozilla.org&redirect_type=single#

Based on https://bugzilla.mozilla.org/show_bug.cgi?id=549040 it seems like it was added because EHLO wants that parameter included and to give the server a clue about who we are, but it's not supposed to be an actual domain. I could be wrong about that.

It seems BenB wrote this code so I'll pass the needinfo on to him :)

Comment 2

[Ben Bucksch (:BenB)]

> it seems like it was added because EHLO wants that parameter included
> and to give the server a clue about who we are, but it's not supposed to be an actual domain.

Entirely correct. :)

Thanks, Ben

Comment 3

[Clément Février]

Yes, it is not suppose to be an actual domain. However, a common configuration to prevent spam in Postfix (and I guess in other mail servers) is to ask the SMTP server an existing domain. This can be configure like that [simplify version]:
smtpd_helo_restrictions =
        reject_invalid_hostname
        reject_invalid_helo_hostname
        reject_unknown_helo_hostname

As Thunderbird is using EHLO to determine if there is StartTLS, the query will fail in that case. That's why a simple workaround is to make we-guess.mozilla.org an actual domain :)

Comment 4

[Andrei Hajdukewycz [:sancus]]

I wouldn't call it a simple workaround given that Thunderbird doesn't control mozilla.org and isn't really part of Mozilla anymore.

If we want this to be an actual domain, imo it needs to be changed to we-guess.thunderbird.net via a patch.