Chick-fil-A sent an email promoting National Sandwich Day on Sunday. Did they forget they're closed that day?

Kelly Tyko | USA TODAY

Show Caption Hide Caption Chick-fil-A apologizes for promoting Sunday's National Sandwich Day Chick-fil-A apologized to customers after accidentally promoting National Sandwich Day on Sunday, Nov. 3. They're closed on Sundays.

Chick-fil-A fans firmly have it ingrained in their minds – and stomachs – that the chicken chain is closed on Sundays.

But the Atlanta-based fast-food chain apparently forgot when it sent an email to some of its loyalty members this week.

"Calling all sandwich lovers," the email that also promoted the Chick-fil-A One program said, "Some prefer it grilled, others fancy the original. No matter which Chick-fil-A sandwich you love, order yours on November 3 for National Sandwich Day."

This year, the made-up food holiday held annually on Nov. 3 falls on a Sunday, which also happens to be the day that rival Popeyes' chicken sandwich – the one that prompted this summer's Chicken Sandwich War – returns to restaurants.

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Another email followed Thursday with the subject, "Well ... this is awkward."

"We recently sent an email that included a message about National Sandwich Day, which naturally we were very excited about," the email reads. "We didn’t realize it falls on Sunday when we are closed. We apologize for the confusion and hope to see you soon (Monday-Saturday)."

In a statement sent to USA TODAY, Chick-fil-A poked fun at its own mistake.

“The cows sometimes get over-eager on their quest for self-preservation," Chick-fil-A said in the statement. "They have been reminded that Sundays are off limits.”

Popeyes took a dig at Chick-fil-A earlier in the week by announcing its chicken sandwich would return on a day the competition was closed.

In a short YouTube video, a highway sign showing Popeyes and Chick-fil-A's names is updated to add the words "open Sunday" under Popeyes, next to the "closed Sunday" under Chick-fil-A.

And Popeyes got another shot in Thursday with a tweet reminiscent of the one that started the Twitter feud. Popeyes retweeted Twitter user's @akareese44 post of the Chick-fil-A email and wrote, “seriously… y’all good?"

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Chick-fil-A's schedule has a fan in Kanye West.

In his new “Jesus is King” album, there's a song called “Closed on Sunday” where he mentions Chick-fil-A with the lyrics, “Closed on Sunday, you my Chick-fil-A. You're my number one, with the lemonade."

Follow USA TODAY reporter Kelly Tyko on Twitter: @KellyTyko