The Midland Certified Reagent Company, Incorporated
The Company for Quality DNA & RNA Oligos
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Email Problems & Issues

If you have sent email to us and it is rejected for some reason or you never get any reply, there are a number of possible reasons your mail didn't get through.

  • If your mail was returned with a message that access was denied, then your Domain or IP Address may have been placed on a black list.

  • Our content filter may have rejected the message.

  • If the email message was infected with a virus or worm which could not be removed, the message will be deleted without any notification that your message was infected.

Due to the fact that we were getting thousands of spams every day, we installed an email filtering system to block all questionable mail. This filtering system uses Black List , Content Filtering and Virus Scanning to block questionable emails from reaching us.

If you are having problems getting emails through to us and you're not sure how to resolve the issue, please call Walter Thompson at 1-800-247-8766 for help.

If you want to find out if you are on a Black List, the link below will be useful to check the listing status on the Black Lists.

  • is a good place to start. You will need to know your mail server IP Address. If you don't know the IP Address, you can use DNS lookup on the top right hand side of the page. Example: If your mail address is, enter and click the lookup button. It should return a page with a box under Answer: with your IP Address listed in blue.

  • Now enter your IP Address into the Spam database lookup (top middle) on the page and press the lookup button. Example: ( Yours may look different. You will get a page which lists all of the black lists and spam lists. Scroll down the page. The only ones you need to concern yourself with are the listings in red, which means that this organization has your domain listed in their database. Each listing will have a link to the listing organization so that you can contact them to get off their list. In most cases you should get your IT / WEB personel to contact them, because it isn't always easy to solve the problem that got you on the list.

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