Benefit emails: consider adding some emails that give, but ask for nothing in return. See the article on marketers as content publishers.
Extra messages, same email: increase message frequency, but not email frequency by piggy-backing on existing communications. For example, adding marketing messages totransactional emails or using sidebar promotions in informational newsletters.
Go with the season: if you're a ski resort, up frequency when you know people plan their winter vacation.
Let subscriber behavior and characteristics drive frequency:Loren McDonald recently wrote:
"When you send email based on your customers' actions or their place in the product or program lifecycle, your messages arrive at logical times."
...to which I would add..."and at the 'right' frequency."
Particularly useful tactics here are trigger emails (like birthday messages or cart abandonment emails) or segmenting out your most active subscribers. If someone is clicking every time you send an email, chances are they'd welcome more.
Give people choice: let people opt-in to another email stream. Or more frequent emails (or less frequent emails). During the 2008 holiday season, for example, RadioShack invited subscribers to opt-in to a dedicated "24 days of deals" campaign. This lets recipients self-select: they tell you directly who wants more (and who doesn't).
Remember, when you start upping frequency, you begin to break expectations built over your previous mails or in sign-up forms. And you start moving along a curve which can end catastrophically.
So you need to change things with care. And you need to combine any increase in frequency with some form of real compensation for the recipient.
All the above do this by upping frequency only when it makes equal sense for the recipient. A change to adjust for different circumstances (e.g. seasonal), to offer more relevancy (e.g. trigger emails), to give more value (e.g. specials and benefit emails) or when the recipient specifically asks for more (e.g. new opt-in streams).
Found on: http://www.email-marketing-reports.com/iland/2009/03/email-frequency-can-you-increase-it.html
