Formal vs informal business email

1. The client will not be available tomorrow.

Contractions: The client won't be available tomorrow

2. They have decided to postpone the meeting

Contractions: They haven't decided to postpone the meeting

3. I have identified three issues

Change commence: I've found three issues

4. Unfortunately, I will not be able to attend the meeting on Friday

Change commence: I'm sorry that I'm afraid that I won't be able to attend the meeting on Friday

5. Performance has deteriorated in the second half of the year

Change commence: Performance began to fade in the second half of the year

6. Thank you for your further information about the study design where you requested on 25th January 

7. I am writing shipment number 8519 for reference

8. I am going to apologize that the product is out of stock temporarily

9. I'm connecting it with your previous mail

10. Please ask me if you need anything

11. It'll be better if you could respond ASAP.

12.  I'd like to tell you...

13. I'm happy to hear that...