Hey Kaushik. Thanks for reaching out to community.
If you or your org uses custom email provider for sending verification or pwd reset emails then I would request you to contact the email provider for the same as E-mail provider uses filtering software with rules that block the e-mail.
Depending on the e-mail provider and filtering software, the steps to solve may vary, but the concept is the same: the receiver of the e-mail or the IT Administrator in charge of the filtering software must add a rule to allow all e-mails from the blocked e-mail address to prevent the e-mail from being filtered to the spam folder. Here is an example for Gmail - Add users to safe senders list
Thanks !!