In our great planet, there are approximately 5,320 email marketing companies. Alright, alright: I'm exaggerating a bit, because I have no idea how many there truly are.

What I do know is that via a Web search you can find a slew of companies that tout the virtues of this email service and that email service and that other service over there in the corner. And here you are: a corporate marketer who has the sole purpose of finding the right company to assist you in providing software and service to get your email marketing campaigns off the ground.

(No wonder so many of us in the marketing biz have gray hairs at an early age.)

Thankfully, yours truly is here to give you an email service provider (ESP) checklist, a handy-dandy guide that you can use whether you're venturing into email for the first time or shopping around for a new provider.

1. Who can you talk to?

One of the nice byproducts of the technological revolution is the ability to connect businesses with their customers in all kinds of different ways: phone, email, SMS, "contact us" form, live chat, etc. The old "operators are standing by" has never been more appropriate.

So something I'd want to know is how the ESP offers support or assistance. Are there varying service levels based on a monthly package? Depending on your level of expertise, you might need more assistance or less, so be upfront with your expectations. As a general rule, most self-service variety ESPs offer the software and a detailed help center for you to answer your own questions.

Realistically, expect to get help during traditional business hours and within an hour of reporting a claim or question, depending on the size of the provider. Sometimes, email groups with smaller client bases can provide a quicker-level of service, while larger firms may have more people to talk with (though they may not necessarily be fully in tune with your account).

2. What services do they offer?

There's a lot that goes into an email marketing campaign, from start to finish. From the software to the creative to the technical to the intangibles, email can be complicated—but it can be simplified if you find an ESP that you can trust.

There are a larger number of groups that focus strictly on the software used to deploy campaigns; that is, you need to use their pre-formatted templates or have your own created by a third party. There are also consultants who can assess email calendars and provide best practices based on their knowledge set, whereas other ESPs offer a taste of everything. Full-service shops are traditionally better, because they can adapt to whatever your business needs are. However, if you have a fully capable HTML designer and a good background in email, one of the self-service options should work great.

3. How much is it?

Since creative and technical services costs can vary based on the project, I'll focus on the actual deploying of the emails here. There are two main ways of how ESPs charge for email sent through their servers: monthly or campaign-based.

With monthly, some ESPs charge based on list size and give you an unlimited amount of sends for a monthly charge, typically under some sort of yearly contract. Others will provide a more custom approach: You pay per deployment and buy the right to send a certain amount of emails out in advance.

There are positives and negatives to both, so if you inform a reputable ESP about your list sizes, your deployment habits, and your needs, the ESP should be able to work with you to come to terms. If not, there is always another one that will.

4. What's their reputation?

According to experts, 95% of all email sent out in 2007 was considered spam, meaning there's a heck of a lot of unseemly people sending out junk email through dirty servers. The quality ESPs will have relationships with an email reputation monitor, a third-party that will monitor email address services providers (AOL, MSN, Yahoo, etc.) to see whether emails are arriving safely and provide blacklist monitoring, pre-deployment spam filter checks and more.

See who your prospective ESPs are working with and what they do to keep the reputation high. Feel free to ask what their latest reputation score is, too. The higher the score, the better their deliverability rates are; so ask what the ESP does to keep itself above board, and look into its partnerships.

5. The Intangibles

What's the list management tool like? Look for easy import and export features, multi-list capabilities, and the overall ability to keep demographic information updated and easy to find.

How are the reports? Does it offer both unique and total opens? How about link tracking? Can you see the hard bounces? Reports are the reason email is such an effective marketing tool, so look for a complete set of reporting tools from prospective ESPs, all available in real-time.

Designing great email. Can you import HTML-built email into the application? Can you design your own in the application? Take a look at the design tools the ESP offers and get a feel for it—so should the people you will entrust to work within the system.

Data, data, data. Does the ESP offer an API that will work with your database? Can you put a sign-up form on your site that'll direct right into your lists? Can you create an auto-responder email for people that sign up to get information from you?

A great host. Is the email application Web-hosted, or does it require an install? If it's not Web-hosted, I'd move on. The ability to create and manage your Web campaigns on-demand from a web browser is a must in today's world.

Honestly, the great intangible will always be your gut instinct. If checking out a company's site or speaking with a rep gives you that not-so-confident feeling, there's probably a reason for it.

In the email space, trust is a huge factor when it comes to that relationship you are trying to grow with your customers and the wrong move with an ESP can cost you more than a few unsubscribes.