Rent increase notification

How should I notify my tenants of rent increase? No reply from my email so far.

What does your tenancy agreement say about rent increases? If nothing, then use a s13 notice, (Govt form 4)

An email is fine, if they accept it & pay the increased amount, then that’s all good. If they don’t pay it though, its not binding. To be binding, you must use S13 notice.