Deliverability is high up on the list of an email marketer's concerns. In fact, a recent report from Jupiter Research, the 2008 Email Marketing Buyer's Guide, found that deliverability is the number-one consideration for marketers when selecting an email service provider (ESP).

Unfortunately, the best ESPs on the market can do only so much to aid in getting marketing messages to the inbox. The majority of the control lies in the hands of the sender.

So what are ESPs good for? They provide the infrastructure that high-volume senders need to get through to the inbox. ESPs should also keep up with the latest in authentication methodologies and provide workflow that enforces current best-practices so senders can rest assured that every message sent is compliant with the best-practices and laws of the email marketing industry.

Although those are essential pieces of the puzzle, other contributing factors to deliverability, such as sender reputation and message relevance, are completely out of your ESP's control.

Perhaps the most important thing you can do is work on your reputation. Think of Internet service providers (ISPs) as bouncers at a private club. If they don't know you or they don't like what you've done in the past, you are going to have a hard time getting into the inbox.

Using a brand-new Internet protocol (IP) address, while seemingly a new start with a clean slate, can have negative impact on your reputation, because spammers frequently change their IP address in order to mask their actions. ISP bouncers are highly skeptical of new IP addresses. However, you can build a strong reputation fairly rapidly by sending consistently good email using the same IP address over time.

Proper list hygiene will also do you wonders for reputation. Before sending any email, ask yourself these questions:

• How old are the email addresses on this list?
• How long has it been since I have obtained permission from these recipients?
• Have too many people on this list unsubscribed?
• If recipient "A" has not opened any of the last five messages I have sent, should I remove her from my list?

You should never guess at email addresses or assume your recipients' preferences. If you're not completely confident that an address rightfully belongs on your list, for any reason, you should remove it. Why? Because poor list hygiene will likely lead to two outcomes: undeliverable email or complaints—both red flags for ISPs.

You recipients can and will complain to their ISPs in a variety of ways. The "spam" button within the user interface is a popular choice. Your customers are overwhelmed by marketing messages on a daily basis, and reporting email as spam is an easy, efficient way for them to clear away the clutter. In fact, many will use the "spam" button as a one-step method of unsubscribing from messages they explicitly requested.

The Email Sender and Provider Coalition (ESPC) reported last year that 80 percent of respondents in their study of consumer email behavior delete or report messages as spam without opening the actual message. Those decisions were largely based on the "from" and "subject" lines.

The holy grail of email marketing is to craft relevant messages that are useful and meaningful to subscribers. Relevance will not only increase your deliverability by minimizing complaints but also lead to higher open rates, customer engagement, conversions and overall return on your investment in the email channel.

Allow recipients to set preferences for how often to email them to ensure that you are not inundating your customers. Make sure you are immediately recognizable in the "from" line and ensure your "subject" line is well thought out and eye-catching.

You can also create automated triggers and transactional messages to turn up the dial on relevance, such as a birthday email, product-replenishment notices, or renewal requests.

Although deliverability is in your hands, consider your ESP your go-to-resource for getting on the right track. From building a clean list to setting up email triggers, your ESP is there to help you increase your deliverability and overall campaign success.