[MlMt] Return-Path when sending message using an alias

[Bill Cole]

On 30 Mar 2021, at 8:13, Glenn Parker wrote:

> I think the answer is yes, but MailMate can't ask Gmail to do it on 
> MailMate's behalf. MailMate needs to do what Gmail does, which is to 
> contact the "alternate" SMTP servers directly to transmit the mail 
> from a different account. You will need to configure MailMate to have 
> a full account for each sender address.

There is also a possibility that this is a domain-level problem with an 
anti-spoofing tactic called 'SPF'. SPF is an acronym for 'Sender 
Permitted From' and is a means for domain owners to publish via DNS 
which IP addresses they know to be legitimate sources of mail with 
envelope senders in their domains (the "MAIL FROM" address, which gets 
put in the "Return-Path" header at final delivery.) GMail may be set up 
to override their internal acceptance of a sender in a domain they don't 
control that has a SPF record forbidding them from sending such email. 
This makes sense for them to do because there is a strong likelihood 
that any mail they send which conflicts with SPF will end up being 
rejected, delivered to a 'spam' folder, or simply dropped.

I apologize for the readability of that paragraph... Put more simply: 
Even if GMail has verified an alternative sender to their own 
satisfaction, it is possible that they are enforcing the policy of a 
domain owner which would otherwise interfere with your deliverability.

-- 
Bill Cole
bill at scconsult.com or billcole at apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire