do you get any error when you send it?
Have you tried removing his contact and sending him a txt just using his number?
Are you using all 10 digits?
Can he send you txt? can he recv from other people?
Can you send to other people?
Are you basing this on not getting the "D" delivery check, or has the recipient truly not received it? I believe delivery notifications are only received when sent to another Verizon customer. Otherwise, follow the above advice and try deleting and adding again.
Thank you all for your replies. Please do try to the suggestions given. We also recommend sending messages using the 10-digit mobile number.
If you are able to send messages to any other U.S. Cellular customer, the issue may be isolated to the one person that is not receiving it. If there are other Verizon Wireless customers that are not able to send this number a text message, it may be an issue on our end.