There are several things b-to-b marketers should keep in mind when integrating promotional content into transactional e-mails. These guidelines can help you achieve your marketing objectives while maintaining compliance and ensuring messages are still deemed transactional.

Follow the two-thirds/one-third rule: More than two-thirds of your e-mail content, whether text-based or graphical, must be information related to the transaction. The remaining one-third may be for promotional use. If you choose to include an upsell or cross-sell message in your transactional e-mails, keep it subtle, relevant and simple. Recipients will not react favorably if they have to weed through copious amounts of commercial content within their transactional confirmations.

Ensure informational content is visually dominant: Do not place any promotional content in the subject line or above the informational content in the message body. Promotional content must be visually distinct and separate from informational content and well "below the fold". That means no banners at the top of the e-mail. However, as long as it's carefully executed, a soft text-based or graphical promotional message in the right-hand sidebar is acceptable.

Maintain brand consistency: Historically transactional e-mail messages have been delivered as plain text, without any dynamic personalization, graphics or links. They tend to look and feel completely different from a company's other e-mails, and are typically handled by IT departments. Consider having the marketing department take ownership of the content and update the look and feel to match other communications.

Don't forget about ROI: Transactional messages, whether they contain promotional content or not, are just as much a part of the customer experience as any other e-mail communication you send. They should be monitored for in-box delivery, and key performance indicators, such as open-rates, click-through rates and post-click activity, should be measured.

Heather Palmer Goff is director of deliverability and ISP relations at e-mail service provider Responsys (www.responsys.com).