[TriLUG] SMTP Submission (port 587) from behind an HTTP(S) proxy

[William Sutton via TriLUG]

how about a Windows VM running Outlook and nothing else?

William Sutton

On Fri, 15 Sep 2017, Matt Flyer via TriLUG wrote:

> In short, my work setup is such that the wired connection gets Internet
> access through an HTTP/HTTPS proxy.  Recently, they switched from using
> a local SMTP server to "smtp.office365.com" and this broke my SMTP mail
> submission in Thunderbird.  To make matters worse, they are using an
> Exchange server, though this seems to be mostly a receive / IMAP
> function rather than a submission one.  I configured Thunderbird to use
> the proxy and it does so for reception of mail, but is unable to
> connect to submit mail.  Off the top of my head I do not know out
> Outlook works in Windows (haven't checked, if I can even tell) other
> that it seems to be some sort of "website" interface rather than real
> email client.  Emails submission from Thunderbird / Linux works fine if
> I am not behind the proxy.
>
> My initial idea as a work around was to configure a relay host on a
> machine that is not behind the proxy and tell it to use SASL
> authentication.  Apparently the M$ servers are "smart" enough to detect
> that this is a relay server and claim that it is not allowed to
> authenticate as a user like that.  
>
> My next idea was to configure my own proxy (squid) in an attempt to get
> an apparent interface that is not behind the main HTTP/S proxy.  I have
> been working on this approach for quite a while and I can see (using
> netstat) the email client establishing a connection to the proxy, but
> it in turn makes NO attempt to connect to the smtp server
> (smpt.office365.com) on port 587 (the TLS submission port).
>
> From what research I have done, the issue seems to revolve around the
> use of the "connect" method in the proxy, but at this point I am
> stumped.
>
> I am not married to any particular solution and willing to try
> alternatives, but I am currently at a loss for what they might be.  
>
> Does anyone have a suggestion for how to "proxy" my SMTP traffic to
> another machine that is not behind this proxy, but that will still
> appear as a MUA (mail client, e.g. Thunderbird) and not a MTA which
> apparently isn't allowed to authenticate.
>
>
>
> -- 
> This message was sent to: William <william at trilug.org>
> To unsubscribe, send a blank message to trilug-leave at trilug.org from that address.
> TriLUG mailing list : https://www.trilug.org/mailman/listinfo/trilug
> Unsubscribe or edit options on the web	: https://www.trilug.org/mailman/options/trilug/william%40trilug.org
> Welcome to TriLUG: http://trilug.org/welcome