Yesterday I used the MassMessage delivery system on Commons to send out multiple messages. All the messages have been delivered except for one (and after this one another MassMessage was sent out successfully). A second attempt about two hours later to the same group of users also was not delivered on the talk pages. With both cases no error message was shown.
The message itself was very similar to the ones to other groups of users (which were received well), only it was translated to Italian.
The group of subscribers is at: https://commons.wikimedia.org/wiki/Commons:Wiki_Loves_Earth_2020/Italy
What did cause that this MassMessage was not delivered?
How can we get this message sent to the listed users?