A passable transactional email focuses on only the event that just happened or is about to happen, such as a subscription request, a hotel reservation, a product order or a recurring payment. A great one describes the event in detail, uses language that makes the customer feel good about what just happened, invites him or her back to the website for more information or to expand on the event, and provides contact information for questions or concerns.
According to Wendy Roth, superior transactional emails include the following elements:
1. A personalized greeting. This is nice for general events like newsletter subscriptions, but it's essential when the transaction involves money, such as a shipping confirmation or hotel reservation.
2. A detailed description of what happened. Not just, "Thanks for your order. Your items will ship soon." Instead, list what the customers bought, the prices they paid, any special instructions, payment status, out-of-stock notices, shipping locations, order numbers, etc.
3. Customer-support contact information, including toll-free phone numbers, mailing addresses and links to online contacts.
4. Other links that encourage the recipient to go deeper into the relationship, including:
- Email newsletters or offers
- RSS feeds for product information or updates
- Loyalty programs
- Offers that cross- or up-sell products that relate to a purchase
- Customer forums, blogs, social-network sites
- How-to information for the product
5. A clear, action-oriented subject line.
6. Any data, except a password, that the customer needs to complete a pending transaction. This may include information needed to pay a bill or go back to a past one, change an order, or update email preferences.
7. All copy in either text or HTML text -- not images -- so that the crucial information is received even if the reader views the message in text on the dinky screen of a low-rent cell phone.
8. A link to your homepage. You never know what's going to drive someone back to your site, and this basic element gets left out more often than you can imagine.
9. A statement about what you will do with the customer's email address, plus a link to your privacy statement.
10. Any terms or conditions that apply to the transaction, such as exchanges and returns, hotel policies or posting schedules for account payments.
Source: iMediaConnection - don't forget to check out the examples on page 2