Problem

After configuring port 25 or 1025, as it is described in the article, the following error appears while sending a test message in Outlook:

Send test e-mail message: None of the authentication methods supported by this client are supported by your server.

Cause

The error occurs if encryption type is not specified in mail client.

Solution

Change the encryption type from None to TLS or Auto :

Open Outlook and click Tools.

In the Tools menu, select Account Settings.

Select your email account from the list and click Change. Email settings should be displayed.

Click More Settings... button.

Select Outgoing Server tab > enable My outgoing server(SMTP) requires authentication and Use same settings as my incoming mail server settings.

Set Outgoing (SMTP) to use port 25 and set "Use the following type of encrypted connection" to "Auto" or "TLS"

For Mac client Outgoing mail server (SMTP) settings -> Use SSL -> Select SSL or TLS

**If you are using secure ports the please set the encrypted connection to "SSL"

Click OK to update the settings.
Click Next and then, click Finish