Short answer: It depends on the day and local holiday status. What today likely means for you

• If today is a regular weekday (not Sunday) and there’s no federal holiday in your area, most USPS mail delivery should occur.
• If today is Veterans Day (November 11) in the U.S., post offices are closed and regular mail is not delivered; only Priority Mail Express may be delivered, and regular delivery resumes the next business day. This year’s Veterans Day falls on a Tuesday, with USPS typically reopening and regular delivery resuming on the following Wednesday.

• On Sundays, there is normally no regular mail delivery unless a special service is in use.

What to check for certainty

• Your local post office hours and holiday schedule (they vary by location).
• Informed Delivery or USPS notices can confirm whether mail is scheduled for today.
• If you’re outside the U.S., check your national postal service’s holiday schedule for today.

If you’d like, tell me your city/state or country and whether today is a federal holiday where you are, and I can give a more precise answer.