Of course we chose Coresender to send our own transactional emails :) So I thought I'll let you know how we use it.
We set up separate sending accounts for all company needs, eg. transactional emails, monitoring alerts, time to inbox. We even configured our office printers to send emails through Coresender.
We have a real-time and extremely usable view into what emails go through each account, so each time anybody reports an email not arriving we're able to assist them in a few seconds
We utilize our message timeline feature, so we can learn eg. if people are clicking on password reset links
We always know how many of our onboarding emails are being opened which helps us improve them
Finally, we have full controll over our suppressions lists, so we can add (and remove!) from them whenever necessary.
To sum up, at Coresender we're eating our own dogfood and it helps us stay connected to the product and understand our customers better.