Hello. I would be very grateful for some help.

Please help me to make the sentence correct:
"Please let me know when the letter comes so that I don't worry / so that I won't worry / for me not to worry / lest I worry."
Thank you.

Please let me know when you receive my letter so I won't worry.

Hello! I'd be happy to help you with your sentence.

To make the sentence grammatically correct and convey the intended meaning, you can use either "so that I don't worry" or "so that I won't worry." Both options are correct and commonly used.

Here's a breakdown of the different choices:

1. "Please let me know when the letter comes so that I don't worry."
This option uses the present simple tense "don't worry" to express a general fact or habitual action. It implies that you tend to worry whenever the letter arrives, so you are asking the other person to inform you in order to prevent your worrying.

2. "Please let me know when the letter comes so that I won't worry."
This option uses the future simple tense "won't worry" to express a specific action in the future. It implies that you anticipate worrying when the letter arrives, so you are asking the other person to inform you ahead of time to avoid unnecessary worry.

As for the other two options:

3. "Please let me know when the letter comes for me not to worry."
This sentence structure is not commonly used in this context and may sound awkward. It implies that the purpose of letting you know when the letter arrives is solely for the purpose of not worrying.

4. "Please let me know when the letter comes lest I worry."
While grammatically correct, this option may sound formal or old-fashioned. The word "lest" means "in order to avoid the risk of." It implies that your worry is seen as a potential problem, and you are asking the other person to inform you to prevent your worrying.

I hope this helps! Let me know if you have any more questions.