I can give you several sentences.
I need to have a letter postmarked today, Vetrans Day, will the post office stamp the letter with todays date tomorrow?
A letter is postmarked on the day that it is accepted by the postal office. It will usually be the same day, but it won't be postmarked for earlier days.
Yes.
It is not envelopes that are postmarked (franked), it is the stamps on the envelopes (so that they can not be used twice). Therefore they are franked when fist processed in the sorting office.
Tombstone Territory - 1957 Postmarked for Death - 1.18 was released on: USA: 12 February 1958
No, that is when they must be postmarked by.
Yes It is
April 15.
i do not know how to use embalming in a sentence. (there is the sentence)
You should put take the envelope to the post office before midnight, or earlier, on that Saturday to get the correct postmark. That is, If the pick up for the mailbox has already passed, your mail will be postmarked the following day of business, which is Monday.
it will be mailed out and postmarked no later then feb1.
So- you are asking when to use 'when' in a sentence. When you are asking how to use when in a question, you are already using when in a sentence, because a question actually is a sentence. I like to use when in a sentence whenever I like.