While I like SendGrid, there are a few things I'd like to note:<p>* It's extremely expensive compared to handling your own email. If you count dollars, what they deliver isn't really worth the cost (expontentially so if you already have your own dedicated sysadmin, which you will want to have anyway). Our app currently sends out around 800,000 notification emails per month, or about $600/mo.<p>* It's been a rocky road. It's been quite buggy for us. I think I had two support tickets within an hour of starting to use it, then another 3-4 tickets open within a week. Things like their email activity and graphs page not working (badly optimized and overloaded, basically); JSON mangling in their API output; and thousands of emails being stuck in their mail server for several hours before being delivered. Everything has been resolved, however, so right now it's fine.<p>* There are some stupid weaknesses. For example, it's not possible to turn off their built-in spam and bounce handling. If a recipient accidentally marks an email as spam (it happens more than you think), SendGrid will simply stop sending email to that user. Similarly, if a recipient's mailbox goes full or has a temporary failure, SendGrid will often hard bounce, and stop sending emails. You can set the expiry times for bounces, but you can't turn them off.<p>Pretty much the only feature that is worth paying for is their stats; they have nice APIs to get stats about deliveries, reads and clicks. So while we are ditching SendGrid for our notification emails, we will continue to use them for newsletters.