Using underscores on email is not a norm in any org. Plus their domain is "mail.mightyrecruiter" this should be more than enough reason to back off. I mean "miGhty rEcruiter"?
Whenever anyone receive a call out of nowhere, and if you're lucky enough to reeceive the mail, always investigate their header value (I know geeky stuff) but it's worth rather than being scammed out of multiplee K's of rupees.
I really hate when people are getting scammed by others instead of me, this was easy peasy, stay vigilent. I won't help the next time!
https://www.forensicsinsider.com/digital-forensics/email-header-analysis/