For over 10 years I owned and ran a dating website for mature people. I now have over 110k members in the database. It was good at first but the last 5 years I got destroyed by the mobile apps and other factors because I was too late. It now makes about 1/3rd what it used to make. Im also burned out on running it and want to do something new. Is this database or website valuable? I'd love to just sell it and put to a new project.
In general, your database has value. Probably very little, but value, nonetheless.
It would have considerably more value if you revived it and were able to prove that you had a viable business and active user base.
While there are investors who buy dormant businesses, you'll find a much larger buyer pool if you have a turnkey business.
All the best,
Selling a database of emails is complicated and almost never a good idea.
Why don't you monetize it through selling solo ads on Udimi or other marketplace?
You can easily have an income, maybe more than what you are currently earning from the database, and get less stress.