May I remind you that ...?
Further to your letter of ...
Could you please confirm the date?
We propose ...
I trust you will find the following points of interest.
I would be very grateful if you could send me ...
Don't forget that ...
Why don't we ... ?
I got your letter about ...
Here's the information you wanted.
Can you send me details on ... ?
Let me know when you have a definite date.
