- Regularly mail your file - Constant communication with your file is the key to building your reputation at ISPs.
- Aggressively handle opt-outs & bounces - This is probably the single most important thing you can do to improve deliverability.
- Use an ESP
- Clean up your code - It's amazing how many companies still sent crappily-coded HTML to recipients. Stop with the Front Page templates and have a professional review performed.
- Use dedicated IPs. A lot of them. The key is to have a range of IPs that you use - if one gets "blacklisted", then you swap in new and cleaner IPs to get your mail through.
- When in doubt, slow down - Throttling your email sends can help prevent some basic ISP blocks.
- Send a confirmation email - Double-opt in is (usually) overkill, especially for sites where you're not doing much except signing up to get email. That said, it's still a great idea to send a confirmation email to the listed address.
Tamara Gielen is an independent email and digital direct marketing
consultant with over 10 years of experience in online, email and direct marketing. 
Swapping IPs frequently and using "a lot" of IPs is generally a bad idea. If you're sending relevant content to subscribers who have opted-in to receive your mail you shouldn't have blacklisting issues that would necessitate swapping IPs.
Posted by: Phil Schott | Jul 28, 2009 at 04:40 PM