Outlook Sends Non Exchange POP3 Mail Using Exchange, 553 rcphostserror results...

[sdelap]

We recently moved one of our clients email servers. They have both
local exchange accounts and external POP3 domain.com accounts setup in
exchange. Domain.com is still their email server but it now has a new
IP. For some reason outlook appears to be sending the external email
through exchange even though all the outgoing servers are setup for
the account to use the external mail server. The emails bounce back
to the internal account with the following error even though they were
send from the external account:

553 sorry, that domain isn't in my list of allowed rcphosts
(#5.5.3 - chkuser)

Is there an option hidden somewhere in outlook to force it to send
external email through the specified server instead of exchange?

 

[Roady [MVP]]

Use the Accounts button to select the correct account to send through.

 

[sdelap]

We have done this already. I have triple checked that we are in fact
sending the email through the external account from Outlook. After we
hit send however it bounces back as if it was sent internally.

 

[Roady [MVP]]

And your version of Outlook would be...?

Make sure you've got your SMTP server for your POP3 account set to use
authentication.