Sending email via an SMTP server of an ISP with authentication..

[Roderick Klein]

I have a customer who uses office 365 E3.

I setup the service in office 365 to fetch his email from different @btinternet.com addresses.

They fetch via POP email and the emails arrive in the customer his mailbox on office 365. That works...

 
However when you send out an email and look in the email header it shows
the returnpath  xxxxxxxx@xxxxxx.onmicrosoft.com

The return path in the header shows this address. Duo to privacy issue's my customer does not want this. So to reply to address is set to his BTINTERNET.COM address. But the header has the returnpath in it.
 

I setup a connector and a rule to relay email via the email server mail.btinternet.com. But as expected the connectors do not provide SMTP authentication.  I have looked at a service such as smtp2go but they do not offer SMTP authenication either. The core issue that in order to relay the email messages via mail.btinternet.com I need SMTP authenication...

So I do not mind if this can still be fixed in office 365 or let office 365 relay via another third party service.

Thanks,

Roderick

[#2]

Hi Roderick,

How is your setup done, what are the configurations ?

Is your domail btinternet.com the default domain ?

Are your users afected with the primary SMTP like btinternet.com ?

[#3]

Do you have enough access to the domain DNS to complete connection of the domain directly into the Office 365 tenant via the Admin Center->Setup->Domains->Add Domain process? This is the only way I know of outside of having some kind of 3rd party forwarding service to allow an outbound email to show from the domain in question. It's much easier though and would be free if you can get access to the DNS profile.

If so you still have to go to Users->(Select User)-> Edit Username/Email Aliases-> configure the "Primary Email Address" for the individual user in order for the default outbound email to match the domain in question.