There have been multiple postings about this topic already, and I know what causes it and when, so it's now a question of - When will Verizon resolve this system issue?
The action taken: - For whatever reason you don't want a certain number contacting you so you use Verizon's MyVerizon web interface or Verizon's MyVerizon mobile app preinstalled on your device to block someone's number.
NOTE: I don't know if it's an oversite on Verizon's part, but even blocked you are still able to send texts and initiate phone calls TO that blocked number and they will receive the text and/or be able to answer the phone call. However, if that number attempts to respond to your post-block text messages or post-block phone calls they are still blocked and will not come through.
The resulting issue: It's seems to be 100% on the Verizon side of things. There is obviously an activity logging function or something enabled in the Verizon system which generates a log entry indicating a failed contact attempt from a non-account number [them] to initiate contact with that Verizon Mobile's number [you]. That should be the end of it.
The problem: For whatever reason, it seems that the system has been set to send out an alert notice of any failed contact attempts made by a blocked number. Since the logging system is basically acting on behalf of that Verizon Mobile account [you], the alert will appear as if it were sent from that Mobile account [you] to the Mobile Account number's device [your phone]. I think that's why the text alerts come to the account user's mobile phone as if that mobile phone's number sent the text.
The suspected cause: There is probably a General Setting in the system that has a simple check box next to "Send alert text to account manager" and a technician checked it. Now the account manager for that number [you] receive alert texts regarding this issue. As for the text content sent in the alert ( "Recipient has insufficient funds to receive message"), it could be something a technician forgot to edit to be specific to this alert or maybe it's just the default alert text their system uses when no other specific text is used. I'm sure the technician could just as easily have entered: "Some wiseguy you don't want to deal with just tried to text you." or a more relevant alert of: "Verizon System Alert - A blocked number was prevented from contacting you." My guess is that the alert text is simply due to a lazy technician.
The possible solution: Verizon needs to update their system and uncheck, disable, nullify or whatever so that the Verizon Mobile number's account [your profile] does NOT receive system alerts [which would be forwarded to your device].
If this has confused you, think of this as something similar to how you can set your Windows computer to notify you of specific issues or don't, and to alert you with a screen pop-up notice or a blinking task bar icon, etc. It’s a system option within Verizon that needs to be turned off.