Hello,
I have installed Elgg 5.1.9 and everything works perfectly except for sending emails to group members.
That is, when a member sends a message to another from Elgg the recipient receives it by email, when a user joins a group they receive confirmation by email, ... all this is correct, but no member of a group receives emails when any content in the group is updated or when new content is created in the group.

I need group members to receive notifications in their email accounts every time content is updated or created in the group, but I can't get this to work.

What could be the cause?

Thank you very much