You can write an adhoc letter to tenants/contractors/landlords on the system
You should be able to find the write a letter function, by going to the office tab and there is a button for Write a letter:
You choose a recipient:
The system will then ask you to check the contact details (so you can choose a postal address)
This will download the letter and give you the opportunity to open the word document.
You can then send this out to the recipient. If you would like to upload the letter to store it in the system, you can add this to the print/post/store documents section of the recipient's profile.