Hey Jaswanth, 

Thanks for reaching out. I recommend that you open a support ticket so we can dig deeper into this issue. 

Having maintenance and support allows you to submit tickets for free. 

This kind of issue usually happens because of a configuration issue. So please open a ticket so we can investigate. 

Thanks, 

Just on the off hand chance someone else finds their way here looking for guidance; spoofed email attacks are often targeted attacks and so can be combated with DMARC primarily. By having a valid SPF record, DKIM record, and DMARC record you allow your email server (and other's) to accurately determine if a sender is allowed to send on behalf of your domain. Getting those set up, and turning on those spam checks in your environment, are a great start to getting these types of problems resolved. 

Hi, but my support and updates are expired, any other way to work on this, please guide me.