Still trying to send the message but nothing happens? Simply it means your message is rejected so that you are not able to send mail. But through this post you are able to solve your problem because here I am share why this issue fluctuates and what are their exact solutions.
1) If we send any message to a large group then Gmail prevents you to send that type of messages. Because this is the problem of bulk mailing that’s why you have to face this particular problem. Here I suggest you to use Google group so that you can easily send the message to your recipients without any problem.
2) In most of the cases third party blacklist can cause this problem. So quickly contact to domain administrator and ask them to configure their mail setting and make you trouble free.
3) Ensure that, if your account has been mistakenly disabled for spamming. So make a connection with contact support to reset your account.