Custom Email Server Issue

I need some assistance here with a custom email server configuration please. When I attempt to set this up with the settings that I know are working for email clients Manager gives me a “Failed Recipients” Message. (The recipients have been checked and are valid).

The working Mail Server Settings for a client are as follows:

ServerName :
Port : 587
User Name:
Authentication Method: Normal Password
Connection Security: STARTTL

I think the issue is perhaps the last two items. Does Manager support STARTTL and Normal Password because if I attempt to connect to the IMAPI Mail server with any other setting for Authentication Method, eg. Kerberos or encrypted or NTLM the Email Client sending mail will fail? Something that is observed and important too, the first time an email client is setup and is connected to the mail server the email client has to accept a certificate. I do know how to OK / accept the certificate in Manager if occurring in the background for the Manager Server edition.

Manager sends email OK when not using the custom SMTP method.

STARTTL is the only security protocol Manager supports so that isn’t a problem.

As far as certificate goes, Manager should be accepting those automatically too.

Have you tried other SMTP server? Perhaps Gmail? Or what you could do is to send me your SMTP credentials to and I’ll have a look if I can spot the issue.

OK I checked the Mail Server and the logs say that the sender address (Manager Company email from address) is rejected because it is not owned by user (Account used to send mail on the Mail Server in the network). Now this has occurred even though the settings are correct in the mail setup of Manager. To circumvent this I think I will need to configure the Mail Server to relay email from my Manager Host system.
So in the meantime I have the email working with the custom mail setup by making certain that the from address is populated with a valid generic account on the mail server such as This is not altogether ideal as I would like each company in Manager to be able to input their own domain from address.
I think setting up the mail server to allow relaying of all mail generated specifically by the Manager Server will resolve the issue?

Your thoughts - Thank you.

OK - all operational. The Mail Server policy has been updated and setup to relay only email from the our Manager Accounting Server and all works 100%. The companies can now enter their own from addresses and Invoices etc are cleanly delivered.
Just one thing, in the Manager Email Settings make certain that the “SMTP server requires authentication” is unticked. Why because the relaying mail server now automatically accepts mail from the Manager Host on the LAN.

Lubos and team - keep up the good work.