Hi MJL, welcome to My Bulgaria!
The opening post was
out of date but has now been altered....
....meanwhile the way to subscribe is to find a property advert on My Bulgaria that interests you and use the 'Click To Enquire About This Property' feature. Once on the enquiry form you will see a box ticked with 'I would like to receive a daily email of new properties.' Leave this box ticked, which then automatically include you on the Property Alerts emailing list.