Everything about Benchmark Email's system is set up so that it is easy for the novice to comprehend while at the same time incorporating extremely powerful features which will suit the most sophisticated user. Benchmark's tracking and reporting interface manages to display extensive information in a clear graphical manner so that you can comprehend how your campaign is performing at a glance, the social media integration is second to none, and their templates are highly sophisticated and attractive. If you ever run into any kind of problem their customer service is prompt, efficient, courteous and knowledgeable. All in all, Benchmark provides everything any email marketer would require... and then some.
Their interface looks great on mobile and smaller screens but gets a bit billboard-y on my 32" monitor.
There are many email service providers but you'll find that once you commit to Benchmark Email you won't ever have to look at alternatives, as they offer it all and do it very well.
We've done trade shows where we have garnered hundreds of permissions from clients to send email and we have found that implementing the double opt-in process with Benchmark results in very high completion rates.