Email authentication issue

[tware6671]

I sent an email via bt webmail to contact@computationaldemonology.com and got the following response

Each of the following recipients was rejected by a remote mail server. The reasons given by the server are included to help you determine why each recipient was rejected.

    Recipient: <contact@computationaldemonology.com>
    Reason:    Please turn on SMTP Authentication in your mail client.                mailomta6-sa.btinternet.com (sa-prd-fep-049.btinternet.com)               [213.120.69.12]:35102 is not permitted to relay through this server without               authentication.

Outlook is authenticating

Does anyone have any thoughts/solutions? TIA.

[gg30340]

You have said you sent the email via webmail then you go onto show the settings on an Outlook email client. If you sent the email via webmail it would have nothing to do with Outlook.

Can you clarify which method you used.

I would also suggest that you remove your email address from the Outlook setting picture that you posted. 

[tware6671]

Good point! First from Outlook, then from webmail to check. Both attempts returned the same message.

[tware6671 · Accepted solution]

FWIW, it turned out the MX records on the receiving server were misconfigured!