Attributing success
Assuming the audience is relatively unchanged, peaks and troughs in email responses are typically attributed to the offer/content and the subject line.
And, naturally, we take that into account when planning future content/offers and writing future subject lines.
But, of course, a proper analysis should consider all the factors that might impact results. And there are a lot more than we generally think.
So when you come to assess your results, cast a wider net when looking for an explanation. For example, review delivery issues, copywriting approaches, timing, the previous emails, your other marketing, spam and the competition.
Read this very interesting article by Mark Brownlow here: www.smartinsights.com

Tamara Gielen is an independent email and digital direct marketing
consultant with over 10 years of experience in online, email and direct marketing.
Excellent post. I try to always question the copy of the emails to make them as relevant as possible, but never thought about considering 'delivery issues' as a factor. Am quite new to this, so your article is helping a lot. I found a few more email marketing tips on this: http://www.b2bm.biz/knowledgebank/email Hope this helps.
Posted by: Joe | Dec 01, 2010 at 09:04 AM