Getting your authentication and welcome emails in front of the user
It’s very important that your authentication and welcome emails get in the inbox and in front of the user. What are the stats you use to define the growth of your site? I’m sure that registered users is often one of those stats. What if your authentication email never made it to your brand new user?
It’s vitally important to realize that if you are just sending email from your server and expecting that it goes in the inbox you are wrong.
Make sure you have an SPF record at the bare minimum, also that you are allowing people easy access to unsubscribe. Also test out your emails, and make sure that you aren’t going in the spam box in the major webmail providers.
Once you have got in the inbox, make sure you are engaging the user. If you are just sending a simple email why should your brand new, eager user authenticate? Are you tracking the click through to your website? How many people signed up and didn’t authenticate?