I know most people don't care, but your sign-up email is broken: there's no plain-text part -- just some crummy html. I'm not sure if the fault is with sendgrid or your system -- either way it's not that hard to have a proper plaintext/ReST/Markdown part, and a html part... (which also encourages testing across the myriad of email clients and webmail providers to see if you manage to generate html that none of them botch up...).