• Thank you for your letter of March 15 ... 
• Thank you for contacting us. 
• In reply to your request ... 
• Thank you for your letter regarding ... 
• With reference to our telephone conversation yesterday ... 
• Further to our meeting last week ... 
• It was a pleasure meeting you in London last month. 
• I enjoyed having lunch with you last week in Tokyo. 
• I would just like to confirm the main points we discussed on Tuesday