Hi,
Is this plugin absolutely necessary, and therefore no 'standard' registered users on my Joomla site can be emailed with it?

If so, can I use this plugin be modified to be able to select/filter whichever type of users we want to email?
Thanks,

- Vince

this plugin is not used to send emails to your guests, but to add the guests to a mailing list in phplist. You will then use phplist to send emails. This is just an integration that will add guest emails (guests who make a booking) to a list in phplist.
Also, all guests that made bookings before you installed this plugin will not be added.

Is this plugin configurable from a property manager perspective? If it's subscribing all the users to a single mailing list then I can't use it. If it permits to subscribe a user to that specific property newsletter, well that is great and I have a use for it.

Right now, each user is added to a list depending on the language he`s speaking/using on the site.

This plugin is not for property managers but for site admins. So users are added to a list id that depends on the site language.

It can be customized though so that instead of a language, a property type specific list id can be used, but customizing it will be up to you.

excellent, thanks! I will customize it to offer individual property managers a marketing tool.