To keep Gmail efficient and accounts safe, Google limits the number of messages you can receive. If your account receives many automated messages, it's more likely your account will reach the message limit.
When an account reaches the limit, you can't receive any new messages. The account might also have general problems, for example slow searching. Any new incoming messages bounce back to the sender.
If you're locked out of your Gmail account, an administrator can:
These Gmail limits apply to all editions and can't be increased. The limits may change without notice.