I got this mail Yesterday, What should i do next?
1.Make sure for creating twitter developer account you need to submit your email address and your phone number to your Twitter account.
2.Please enable the email-notifications and the mobile notifications that you have provided to the twitter account.
3.And in case if you deactivated your twitter account that needs to link with the developer account you can send a request to process a developer account.
4.You can also send multiple requests in case you failed to do with the previous case.
5.Its better you again create a request and soon they will notify you again from Twitter developers account and also from the same sender you got a mail from.