When you encounter the “ERROR: Unable to deliver message” notification, it may be the result of a variety of factors that are preventing the successful transmission of your message.

1. One possibility is that your mobile phone is currently not functional or has no network coverage, rendering it offline and unable to receive messages.
2. Alternatively, there’s a chance that you could have accidentally removed your own phone number from the system’s subscription list, which would stop the service from being able to send messages to you.
3. Another explanation could be that the content of the email message we endeavored to route to the recipient didn’t adhere to strict content regulations, commonly referred to by the acronym S.H.A.F.T., which stands for sex, hate, alcohol, firearms, and tobacco. Such content is closely monitored and regulated to prevent the distribution of messages that promote or feature any of these sensitive subjects.