The right e-mail at the right time can be a powerful touch point with your customer. At its best, meaningful e-mail content can complement the salesperson in-store and extend the reach of their relationship with customers.

I've been flying a lot this month, both for vacation and business, and e-mail updates for upcoming flights have made the experience smoother.

During the recession, companies launched e-mail campaigns in record numbers because it is cost-effective and measurable. According to a study by Forrester Research, spending on e-mail marketing in the US will balloon to $2 billion by 2014. In many cases, marketers are opting to shift marketing money from traditional media to interactive marketing.

Forget all the claims that one day or time is better than another to send messages to your mailing list. The ideal time to send e-mails, of course, is when each recipient is most likely to open and act on your e-mails.

Using e-mail to cross-promote multiple brands can be tricky, but when done right, it can noticeably increase ROI. The idea behind any co-branded effort should be for both brands to partner in a clever way that makes the joint experience better than either brand on its own.

The most opened, read, and acted upon e-mails are automated e-mail campaigns. Marketing Sherpa reports an impressive open rate of over 50% on automated messages, compared to a typical open rate of 20% in 2008.

E-mail is as vital and important a part in the direct marketing toolkit as ever before. Competition for the scarce attention of consumers remains intense as marketers devise ways to make brand messages stand out amid cluttered inboxes. So, it is particularly vital that marketers take advantage of the consumer's broader media and communications ecosystem as part of the evolving role of e-mail marketing.

The Sidekick data loss incident is prompting questions about how safe cloud-computed data really is. Earlier this week, users of T-Mobile Sidekick phones with the Danger Inc. service lost all of their contact and system data, which historically has been backed up in a cloud system.

One of the fundamental requirements of a successful e-mail marketing campaign is understanding how your customers interact with your e-mail. Yet this kind of behavioral data is hard to come by. How often do they look at their e-mail? What else is competing with your message in the inbox? Do customers view the message in the preview pane? Are they seeing images?

With social media playing a more important role in consumer communications than in the past, the inbox is now defined more broadly. It is no longer just for checking messages in one portal, but finding different kinds of messages from various places on the Web.