These two Email Service Providers (ESPs) are as different as they can be.

Aweber is primarily an auto-responder service, enewsletter service second. To take advantage of all its features, you really need to be familiar with some Internet technologies, such as HTML, FTP and RSS.

If your intention is to self-publish a company newsletter, then Constant Contact is a better choice (not the best choice, though, but read on). They have an extensive library of ezine templates which can be customized relatively easily. CC provides hosting space for a small number of images, and more can be purchased. Aweber does not offer image hosting, so images need to be uploaded to your web site or blog - by FTP, for example.

When sending HTML emails, such as newsletters and e-flyers, it is advisable to also send a plain text version along with it, for people who prefer to read text-only emails, or their email programs don’t support HTML, or HTML is blocked by the company firewall. If you’re using one of Constant Contact’s many templates, the system generates the TXT version for you. With Aweber you need to manually create the TXT version which can become tedious quickly. However, a tool such as Premailer can help with that, however your HTML ezine needs to be hosted on your web site for this tool to work.

If you plan to publish several different email newsletters, and collect subscribers online, then Aweber provides an easier way, as you can have separate sign up forms for each list (newsletter). Aweber also offers pop up sign up forms, which have been proved to be very effective. Also, in terms of user experience during the sign up process, Aweber offers more choices as you can direct subscribers to different pages on your site, for example to deliver a sign up bonus or freebie.

Constant Contact would be a better choice if you already have an existing list of subscribers, or clients, which you can import into your account. Ideally you would import only people you know would be interested in receiving your newsletters, and have given you permission (either electronically or in person). When importing any number of contacts into an Awber account they are automatically sent a so-called “confirmation” email. This email contains a link each individual contact must click to give you permission to send them additional messages. This process can sometimes decimate your list, even ones which contain previously confirmed contacts. With Constant Contact, it’s up to you if you want to send your contacts this message, or you can confirm them “softly” over time, by including a “reminder” at the top of each email you send them. When a confirmation message is sent, you can not send your contact ANY more messages until they click on the confirmation link.

If it’s important for you to get detailed reports on opens and click-throughs, CC comes ahead of Aweber again. CC offers a very detailed report on how many people were sent an email, how many (and which ones) were opened, who click on which links, and how many times, who forwarded your email to a friend, etc. Aweber (in its basic package) offers limited reporting capabilities, to get the similar reporting to Constant Contact’s you need to upgrade your account.

If you’re looking for a system to easily create and send email newsletters and e-flyers, consider MadMimi instead of Constant Contact, as it’s much easier to use, at about half the price.

For a full-featured, yet easy to use auto-responder and newsletter publishing system I know use and recommend iContact.