Create Your Own Email Spam Filter
If your spam and Gmail newsletter filters are letting in too many messages, or if you are using a private email service with a poor spam filter, try the next solution: Quarantine all email until the sender confirms it is not spam . This is your homemade spam filter.
Blogger Beetle B. set up its mail server to automatically reply to every email from a new sender. The response includes a link that leads to a site where the sender must enter their email address to confirm that they are not a spammer.
It’s a little annoying for the sender, but not very painful, so Beetle B. didn’t stop me from receiving important emails. They’ve been using the system for over a year and so far it works well enough to recommend it to anyone frustrated with spam and low priority email. They go on to list a few services to help you create your own autoresponder without a ton of work.
If the sender does not fill out the form, their email is sent to the quarantine folder, much like a regular spam filter. Beetle B. checks them daily and still finds it much better than the old way of digging into irrelevant emails and not responding to important emails for months.
If you are worried about important emails not reaching you, you can mitigate this with a whitelist. When Beetle B. launched their system, they first whitelisted everyone they emailed. You can set your own criteria for whitelisting. Beetle B. made their whitelist quite large, which skipped some unwanted newsletters at first, but they just removed those newsletters from the whitelist as they came in.
Solving the problem with my email and next steps | Beetle Cosmos