Having a problem with recipients @Yahoo, Aol.com or Verizon.
Make sure you register your sender domain at Yahoo complaint feedback loop.
A Feedback Loop is a tool that enables complaints to be automatically recorded in your account as unsubscribes.
Setting up a Yahoo complaint feedback loop (YFBL) helps with your delivery to yahoo.com recipients. If a yahoo.com recipient marks your message as spam, you do not want to continue sending to that person, so having that address automatically unsubscribed from your account helps prevent continued sending to recipients that no longer desire your emails.
Not having the Yahoo complaint feedback loop can lead to having a low reputation for your emails that cause hitting spam and getting messages delayed to get delivered or even not delivered at all.
How to set Yahoo complaint feedback loop
This can be done as follow:
Access the Yahoo Feedback Loop Page here. You should arrive on a page like this:
Complete all fields on the page, as follows:
To submit your information, click Get Verification Code.
Leave your browser tab open on the next page and go to your inbox for the postmaster@your_sending_domain.com
Now we can handle Verizon media complaints about your account. You can find complaining recipients in your dashboard under "Reports" under "Spam reports"