Messenger app internet msg and satellite msg are both counted toward monthly count in explorer website.

The manual tells something different:

„Messages sent using a wireless connection or cellular data on your phone do not incur data charges or additional charges on your inReach subscription. Messages received may incur charges if message delivery is attempted over both the Iridium satellite network and the internet. Standard text messaging rates for your cellular data plan apply.“

I am using an Expedition subscription plan, so I don’t see this and can’t take a look on it.

So satellite messages always counts again your plan.

Exactly, that's what I was expecting.  I've even sent a couple of test messages via the app without the iReach Messenger device powered on, and they were delivered to an email account and they reduced my current monthly usage message count by two on my explorer home web page.   Not sure about billing charge yet as I haven't used monthly allowance of 40 on the Freedom plan.

Yes, the test message type is “Internet”, not satellite.  This is the android app.  I’ve setup the app on an iPad with wifi only and test again with the inreach messenger device turned off.  The message was sent successfully from the app, and my current monthly usage count for Messages was reduced by the one message sent. .  Since I haven’t gone over the 40 included messages in the Freedom yet, I’m not sure of billing, but it appears all messages sent to a contact that’s not mapshare is affected the current message count.

This sounds like a bug on the server side. You should probably open a support ticket. Certainly something is wrong if you are being dinged for a message sent via Internet (rather than via iR satellite).

That said, I believe there are uncertainties, especially with regard to received messages. I don't understand how the servers decide which way to send a message TO the device. I would not be surprised to find that satellite gets attempted in some cases where you would not necessarily expect it. Even with regard to a sent message, there may be corner cases where you have no Internet/cell connectivity and the device is off. Transmission is delayed. Depending on what you do first (re-enter cell service, power the device up, or whatever), this might result in unexpected iR traffic. Just guessing, though. The whole process is a mysterious black box.

So the user has no overview, how many sent/received messages have count against the plan and how many free ones are left! This functionality is also not working (it is available on the devices!) on the iR devices. You always only get  - -

(Again) From the messenger manual:

Viewing Data Use You can view the number of messages, check-in messages, and track points sent during the current billing cycle. The data use counter resets automatically at the beginning of each billing cycle. 1 From the home page, press or to scroll through the main menu options. 2 Select Service Plan > Data Use.

It just don´t work (nor on mini 2 or gpsmap 66i) ; if they will get it to work, it should show also received messages, because they count against your plan.

Just registered my device tonight and I am experiencing the same issue so you are not alone.  I will be testing it tomorrow but wondering if in the messenger itself if you go to Data Use > Messages Sent it will give any details, fingers crossed are really annoying not knowing how many messages you have left especially as I am off on a 36 day adventure end of April

Yes, the message detail does indicate if it's a satellite or Internet message.  The Explorer website does not separate or only count satellite messages so it not useful to determine how many satellite messages remain, but the inReach Messenger app has been enhanced to show remaining satellite messages.  It is helpful but I think it only updates when the app refreshes with an Internet connection as it didn't update when I was out of range for a few days, but did when I returned.