Jim said:
I am on a single Gmail IMAP account.
I also have a domain address whose catchall redirects to my Gmail address.
The Outlook account is set up as my default domain address and the SMTP is
Gmail
Outlook 2010 has a 'From' bar into which I have put a couple of addresses
eg (e-mail address removed). I want people to post back to that address which is
what happens OK if I post from eg Yahoo Mail.
Alas, Outlook will not completely lie to the recipient as to what you
claim is your e-mail address when using the From field when composing an
e-mail. The value you specify will get put into the From header but
Outlook will also add something like an "On behalf of" header (I forget
what it's called). So the e-mail account defined in Outlook through
which you send your e-mail will be identified in another header while
the From header shows what you wanted the recipient to see and use.
As I recall, Gmail adds its own headers that will identify from what
account an e-mail originated from there. Despite what you had your
client insert in the From header (which is transferred in the DATA
command by your client to the server along with the body of your message
and why it cannot be trusted to be the true source of an e-mail since
the sender gets to specify it), Gmail adds the following header:
Return-Path: <youraccount>
Gmail isn't looking inside the data of your message to see what your
client specified in the From header it added. Gmail prepends its own
headers, like this one, to e-mails you send from their service. So the
recipient can still see the Gmail account from which you originated an
e-mail. While Outlook lets you try to lie, or redirect replies to
elsewhere, using the From header (a client specified header, not one
added by the server), some e-mail providers will still identify the
sending account using their service. As long as your recipients don't
look at the headers then they don't know the e-mail came from somewhere
other than claimed.
Most users just see the From header (what you or your e-mail client
specified which is nothing the server inserted). When they reply, that
is to where their message will go UNLESS you specified a Reply-To header
(also something you or your e-mail client adds, not the server). So
perhaps you configured the account in Outlook with a non-blank Reply-To
value. For each account you defined in Outlook, check its properties to
see if you specified a non-blank value for the "Reply E-mail" field.
That's what goes into the Reply-To header.
Could be the Yahoo account defined in Outlook has a blank Reply-To value
while the Gmail account defined in Outlook has a non-blank Reply-To
value.