In certain circumstances, you might not be able to enter the code to verify your mobile number during sign up (due to session expiry, verification code reception problems, etc.). You will not be able to sign in if you haven't verified your mobile number. In such cases, login to mail.zoho.com using the mobile number you entered, and the password used during sign up. In the Verify mobile number page, click the Resend code link and enter the verification code that you receive. Learn more.