mail Error

I am sending a messagae from gmail to another domain mail account. Some time mail deliver,some time show the error that
1 ” You should get this bouncing facility checked by your people.b ”

2 “delivery to the following recipient failed permanently”

3 ” Gmail tried to deliver your message, but it was rejected by the recipient domain ”

These are the Errors and some time deliver the mail to the same person without any errors.

Plase send me the tips to avoid this problem