Hi Hacker News!<p>I'm the co-founder and CEO of Medical Joyworks (the company which created Vetter). You might be wondering - why is a <i>medical education</i> company building an inbox delivery tool?<p>Well, we have a 150+ international medical board (specialist physicians who peer-review our medical education content). We communicate with them both directly as individuals, and as a group via a mailing list.<p>We've found that some of our emails tended to end up in spam, despite their content being very much non-spammy - and even though our email domain has neutral reputation (we just don't send a lot of emails!); and we've got SPF, DKIM, etc. setup. We even tried to validate our emails against SpamAssassin - but our scores were extremely good (-1 or lower).<p>We figured that instead of dealing with tools that try to guess whether your email might be spammed, we might as well test our emails against real email accounts. So, we hacked up a set of scripts to send emails from our domain to a set of Gmail, Hotmail, Outlook and Yahoo accounts, and just started playing around.<p>We were kinda shocked to see how trivial changes in an email's subject and body could massively affect inbox rates. In fact, Microsoft's email services (Outlook, Hotmail, and Live) were consistently sending our emails to the spam folder. Thanks to our tests scripts, we managed to adjust our emails' subjects/bodies to get 90% to 100% inbox delivery.<p>Because these scripts turned out to be so useful for us, we thought of turning them into a proper tool that anyone else could sign up for and use - hence Vetter.<p>Thanks for reading this. I'd love to read your comments and feedback - whether good or bad!