The most reliable technique to ensure that mail is postmarked by midnight is to present it in person to a post office before the last mail collection of the day and before the post office closes for the day. Some post offices are equipped with automated postal centres that deliver the necessary postmark.
Numerous individuals needing postmarks by midnight on a particular day are attempting to ship their tax returns before the IRS deadline. Because so many people now submit their taxes electronically, fewer post offices are open until midnight on tax due dates than in the past. Applying a metered time stamp to obtain a postmark before midnight and then delivering the letter to a post office at a later date will likely result in the rejection of the mail.