Agreed. Only at a huge scale is a custom made e-mail solution time or cost effective. Obviously the blog post was only talking about how effective it is for 37

Agreed. Only at a huge scale is a custom made e-mail solution time or cost effective. Obviously the blog post was only talking about how effective it is for 37signals, but I fear many young startups will misinterpret it and waste a ton of time rolling their own mass e-mail solution.