I have recently been told about Tenant Txt, a web-site which landlords (particularly those with a large number of properties, and social landlords) can use to contact their tenants.
The landlord signs up to the web-site, and also signs up his tenants. They say whether they want to be notified via text, email or twitter. Then every time the landlord wants to notify them about something he can do this via the tenant txt website.
The site suggests that it can be used to remind tenants of important maintenance repairs, alert people if there is crime in the area, and inform tenants of community events.
If as a landlord you send out a lot of paper notifications to your tenants, this will certainly save you money on paper and postage, and therefore could be worth trying. With the higher subscription prices you can also use it to alert your office and maintenance staff.
There is an initial free trial period, and after that you have to pay. The prices are in American dollars as this is an American site, but that does not mean it cannot be used for British properties. If you try it, post a comment here and let us know how you get on.