After initial installation, MailEnable is unable to send email


After initial installation, MailEnable is unable to send email.


There are various reasons why this can occur:

  • SMTP Relay settings
  • Incorrect credentials
  • 'My account requires authentication' not enabled in Outlook.


  • On a new install, MailEnable sets the following relay settings

    -Allow relay for authenticated senders
    -Allow relay for privileged IP ranges

    The first option, Allow relay for authenticated senders means that only email clients that send a username and password of an active MailEnable mailbox will be able to send email to a non-local email address. So in order to send email to non-local addresses, SMTP authentication needs to be enabled on the email client.
  • If SMTP authentication is not enabled, the message "503 This mail server requires authentication. Please check your mail client settings."  will appear when trying to send email.

    In Microsoft Outlook and Outlook Express SMTP authentication can be enabled by setting the My server requires authentication checkbox in the account settings. The Allow relay for privileged IP ranges allows the IP address to relay email without sending a username and password, in order to allow programs and websites on the local server to send out email.
  • Ensure that the username to login to web mail is formatted in the following way: mailboxname@postofficename and not mailboxname@domainname.


Details on relaying can be found at:

Email clients which do not support relay can be found at:

Product:MailEnable (All Versions)
Class:PRB: Product Problem or Issue
Revised:Wednesday, May 4, 2016