How to send out mailings to "unconfirmed" addresses?

Question

Email

Hello.
There is a base of 6,000 subscribers, which was collected over 4 years, using various sites with subscription forms.
Now we want to organize a mailing list on this database, we turned to Unisender, where we were tactfully refused, referring to the "unconfirmed" addresses. We failed to prove "confirmation".
Who faced similar? how to send mailings to a long-established database?

Answer 1

If you did not validate the addresses when subscribing, and if the addresses are not associated with real transactions, which are definitely real people (for example, an order for food delivery), then there are more garbage in your database than real subscribers. Users subscribed "on different sites" and 4 years ago, so it's unlikely that you want to send them what they subscribed to, even if they still remember that they subscribed to something. In total, what you want to do differs little from regular spam, which is what Unisender is hinting at.
Throw out users who have not been active for more than a year, leave only those who are definitely not a bot (for example, there are confirmed transactions or belong to the core of visitors), subscribe in the future as a double opt-in with an explicit indication of what you are subscribing to and interact with users immediately while they are still warm.

Answer 2

knock here: https://vk.com/mymails