How many emails in your list?

We are looking at emailmovers dot com to do a test similar to what you described. So far they sound good, but too early to tell if it will work in the end and give the ROI we need

I would have reservations about your responsibilities to protect your customers' privacy when you turn over their information to a third party. How does that meet with your published privacy policies?

Some such services have been known to add your list to the list they sell to others or market to for their own clients. I would thoroughly check my responsibilities before turning the work over to an outside entity, and thoroughly check on their own reputation. The software companies that you mention make sure you never have that worry.
_{(disclaimer - I have no specific knowledge regarding the spam laws of any country that prohibit hiring a 3rd party, just my own consumer concerns reflected here)}

I came across this website that seem pretty legit but they currently don't send emails for my current niche. Hopefully they expand and start offering other verticals that they will send to.

[outboundengine.com...]

Thank you!