My domain want to buy

Dear, Habr! Please resolve my doubts. They want to buy my domain, which they notified me with a letter. Should I somehow react to this email, or should I just ignore it? I don’t want to give or sell a domain, because a soul has been invested in it and it is not for earnings. Please help me with advice. Thank!
Further text of the letter:

Dear Sir,

We are interested in buying a domain NAME.RU and usually offer from 50% to 65% of the assessed value.
We accept ratings from companies like

www.sedo.com
top-name.net
')
If you already have a rating please send it to us.

Please let us know your interests. After reviewing your estimate, and in case of an agreement, we send payments through PayPal for an amount of less than $ 2,000 and via Escrow.com for amounts over $ 2,000, as well as further instructions on the full transfer of the domain name.

Thank,

Domain Trade LLC

Dear sir

and usually offer between 50% and 65% of the appraised value.
We accept appraisals from companies such as

www.sedo.com
top-name.net

If you already have an appraisal, please forward it to us.

Please let us know how you are interested. We will send you a payment of less than $ 2,000 and a sum of $ 2.000.

Thank you,

Domain Trade LLC

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The domain name, of course, is not NAME.RU. If someone is interested, I will inform you the real name. Just did not want to promote.

According to the results of the answers: People who send such letters, either promote the site indicated in the body of the letter, or offer paid services. And place such letters in the folder "Spam". By the way, came the second message of similar content. Ask to sell another one of my domain.
Many thanks to all who answered!