Here are some very good credit safelists. Most of them send to the contact email address and are very responsive.
As an Internet Marketer, I use many advertising sources. I do not want to overwhelm you by listing too many websites, but I also know that we are all different and like different types of things. Please look at these and join the ones you feel you could use daily. They are free to sign up on.
Mister Safelist — Very good results. Definitely a must join for anyone wanting to get sales and signups.
Puffin Mailer — Easy to use with good response rate.
List Volta — Totally passive advertising. Send ads for free. However, if you grab the Infinity upgrade you can enter two solo ads in to be submitted for you daily. You can then update your ads or change them however you want. Pays nice commissions, too.
Herculist — Send solo ads daily. This is an exceptional way to advertise. They even offer very good extra solo ads. Very high quality. Also pays very nice commissions.
Ad Troopers — I have been a member of Ad Troopers for years. Very high quality and one of my favorites. I get a great response.