Mail Delivery Status Notification (Delay)

Mail Delivery Status Notification (Delay)

Hi all,

I am having problems sending my emails.

I am getting this email back: Mail Delivery Status Notification (Delay)

And when I look at me send box and click on the send item, I see:

In Retry Queue
Temporary failure when delivering email to the recipients. Emails in queue will be retried automatically.

Host not reachable.

What can I do?