If you see an alert that your message was delivered as junk
iOS 13.3 and later include improvements to minimise junk messages in the Messages app that may impact certain messages you send.
If your message was delivered as junk
If you’re trying to send a message to someone and you see an alert that says the message was delivered as junk, here are some things you can try:
Ask the person you’re trying to message to add your phone number to their Contacts.
Ask the person you’re trying to message to send you a message to start the conversation.
On your device, go to Settings > Messages > Send & Receive and make sure that only your phone number is selected under Start New Conversations From. If your Apple ID is selected, the messages will be delivered as junk.
If you're on an iPad or iPod touch, turn on Text Message Forwarding from your iPhone.