PITTSBURGH (KDKA) — Attention Columbia Gas customers!

There’s a letter in your mailbox you do not want to ignore, especially if you don’t want to be solicited by other natural gas suppliers.

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“Through this letter that was sent to our customers, we are providing customers with the option to have their customer information removed from a list provided to natural gas suppliers,” Columbia Gas spokesperson Sarah Perry told KDKA money editor Jon Delano on Friday.

Perry says the company is giving all customers a chance to opt out of the mailing list given to other gas suppliers.

But here’s the catch — the failure to act means you’ve opted in — you can’t just ignore the letter.

So what gets given to companies marketing to you?

“Your Columbia Gas account number, the name on your account, your service address, your mailing address, and whether you are a residential or commercial customer,” says Perry.

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That does not include your telephone number which remains private.

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But here’s another wrinkle.

Even if you’ve already opted out, you have to do so again.

“We are sending out these letters for the first time to now customers who in the past have opted out.”

So why is Columbia Gas sending this letter out to all 400,000 customers?

It turns out that it’s not the gas company’s choice. It’s a requirement of the Public Utility Commission.

“Once every three years, the distribution companies are required to reach out to all of their residential and small commercial customers,” says Nils Hagen-Fredericksen with the PUC.

Under a new PUC requirement, every gas and electric utility company is required to do this update.

“Customers can opt out in three different ways. By calling our customer service number, by returning the insert that was in their direct mail piece, or by going to the Columbia Gas of Pennsylvania website.

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September 1st is the deadline to opt out, and so far only 4,500 of the 400,000 have done so.