whenever i try to send a mail, a screen occurs for verification.. why it happens.. kindly clearify?

Question

whenever i try to send any mail a screen occurs like plese enter the no.. or words shown in the box for verification, kindly let me know why it happens..
my email id is [e-mail]

Answer 1

you are trying to send to multiple addresses or you are using a subject line or content that makes the email filter thinks you are spamming.

Or you are spamming.

Answer 2

even i m wondering!