If you have configured Custom Email Server under Admin > Channels > Email, you may sometimes encounter the following SMTP authentication errors:


1. “Error while authenticating the SMTP server. Please verify server name, port, and credentials,”


If you are using Microsoft O365 as custom mail server option, please check if SMTP is enabled on your mailbox.

  1. Open the Microsoft 365 admin center using O365 credentials and go to Users > Active users.
  2. Select the user with the custom mailbox configuration, and in the flyout that appears, click Mail.
  3. In the Email Apps section, click Manage Email Apps.



  4. Ensure “IMAP” and “Authenticated SMTP” are enabled in the Manage email apps window. As in the screenshot, verify the Authenticated SMTP setting: unchecked = disabled, checked = enabled. 

    Keep the setting as checked.


  5. Once, click Save.


In the case of Gmail, please check your IMAP and SMTP settings under Gmail account > Settings. This should help configure the custom mailbox successfully. 



Note: Most newer O365 tenants have SMTP authentication disabled at the tenant level by default. You can enable it by inbox if desired. It takes about 30 minutes for the permissions to take effect. Reference.



2. "Freshdesk is unable to send emails for custom mailbox; Please reauthorize"


An email notification with the aforementioned error is triggered when there is a timeout error and Freshdesk tries to connect with the SMTP server of your mailbox. To resolve this issue, please reauthorize your custom mailbox from under Admin > Channels > Email. Here is an article for help.



3. "Something went wrong. We are unable to connect to your custom mailbox. View details"


Similarly, the above banner would be shown in your Freshdesk account when Freshdesk tries to connect to your mailbox and if the connection is not passed successfully. To resolve this issue, please reauthorize your custom mailbox from under Admin > Channels > Email. Here is an article for help.