I'll post the letter when I go out.

我出门时去寄这封信。（英国英语）

He reminded me to post the letter.

他提醒我去寄信。

Can you post the letter for me?

你能替我把这封信寄了吗？

Please post the letter to him.

请把这封信寄给他。

I want you to post the letter.

我要你去寄这封信。

Please help me post the letter.

请帮我寄出信。

She forgot to post the letter.

她忘记要寄这封信了。

We will post the letter soon.

我们马上会寄那封信。

Shall I post the letter for you?

要不要我为你寄这封信？

Post the letter at once, please.

请马上把这封信寄了。

Remember to post the letter.

记住把信寄了。

I remembered to post the letter.

我没有忘记寄那封信。

Could you post the letter for me?

你能帮我把这封信寄了吗？

Shall I post the letter for you?

要我把信替你寄出去?。

I'll remember to post the letter.

我会记着去寄信的。

He said he would post the letter.

他说他将要寄这封信。

He got his son to post the letter.

他叫他儿子去寄信。

Please remind me to post the letter.

请提醒我寄那信封。

Please remind him to post the letter.

请提醒他别忘了寄信。

Will you please post the letter for me?

请帮我寄了这封信好吗？

Will you post the letter for me, please?

请帮我把这封信寄出去好吗？

I can post the letter for you in passing.

我可以顺便帮你寄信。

Please remember to post the letter today.

我记得今天把信寄走了。

Sorry I forgot to post the letter for you.

抱歉，我忘了替你寄这封信了。

Please remember to post the letter for me.

请记住替我发了这封信。

Please remember to post the letter for me.

请别忘了帮我把信寄一下。

Please remind me to post the letter tomorrow.

明天请提醒我寄信。

I would rather you post the letter right away.

我倒宁愿你马上把这封信邮走。