Hi Bhavana

I'm assuming this is a scheduled task that sends a mail with a report attached to it.
In this case I would try the following:

• Can you double check the SLScheduler logs at time of execution?
  You might want to increase the log level to 5 and try again.
  Given the successful execution, I expect no issues here.
• Verify that the SMTP settings are correct:
  Configuring outgoing email | DataMiner Docs
  (if the mails did work before, then I suspect this should be ok, i.e. if nothing changed.)
• If you create a scheduled task with only a basic mail, no reports, just plain text. Does this fail as well?
• If you test this via Automation? Again, simple script that sends a basic mail, does this work?
• You can also work together with your IT department, they should have visibility on what comes into the configured mail server, e.g. via the messagetrackinglogs, then you see what comes in, from where, how it went,...