Validate Email address with sign up before sending verification emails

[mohamed-abdelrhman]

Issue Description

within sign up method we use SendGrid to dispatch email verifications to the new users.
currently, the server does not perform any validation checks if the provided email addresses are valid.
which can lead to spam our send-grid plan.

Requirements

Before an email verification is sent out, the server should validate the email address

Proposed Changes

Implement email verification strategy that implements

• validate email syntax errors
• look for non-existent or invalid domains
• identify spam traps real-looking but invalid addresses