3341119 - No email is sent from IAS when using custom mail server

• Example scenario:
  Following text is displayed when logging on to the IAS tenant:

  "Your Password Needs to Be Reset
  An e-mail with a link to reset your password has been sent to xxx@companyname.com. Your password has not been used for more than 6 months. 
  To help maintain your security, your password needs to be reset. We have sent an e-mail to your e-mail address containing a link to a page where you can reset your password. 
  The link in the e-mail will expire in 2 hours from now."

            

• User does not receive any email and when checking the logs, following error can be seen (mail subject is an example):

  "2023-06-02T06.18.55.055Z timestamp="2023-06-02T06.18.55.055Z", ipAddress="<ipadress>", severity="INFO", location="umtrace", crtAccount="<TenantId>", authenticatedSubject="anonymous", 
  correlationId="E3533657-A74C-4648-A78C-93ED1CB50D55", state="failed", action="sendMail", objectType="user", objectId="xxx@companyname.com", 
  message="Sending the email to the following server failed :<mail server>", category="audit.configuration", mailSubject="How to reset your password", 
  currentPoolSize="300", currentActiveThreads="1"

              

Configure custom mail server, Email could not be sent to, Sending the email to the following server failed, smtp.office365.com:587, Authentication unsuccessful  , KBA , BC-IAM-IDS , Identity Authentication Service , Problem