Below are the possible reasons that you may not be able to send emails:
Reason 1: You have not added "Email Marketing Account".
Every organisation registered for email marketing service is given a unique email id on the MTowerBee.com domain. This enables every organisation to build their own email id reputation.
Reason 2: You have purchased the email ids
Our system constantly checks your subscribers list against various purchased database of email ids. In case, your subscriber list matches with the purchase list of email ids, you will not be able to send out email. Your account may also be suspended. Hence, we advise users and organisations NOT to use purchased database of email ids to create a mailing list.