More than one-half of US e-mail marketing executives get 20% or less of their firm's e-mail budgets, according to StrongMail Systems and JupiterResearch’s “Maturation of Email: Controlling Messaging Chaos Through Centralization” report.

E-mail marketers appear to get shortchanged when it comes to e-mail budgets, especially considering the medium's wide usage. JupiterResearch found more than one-quarter of the e-mail that consumers received in their inboxes was marketing. But there are reasons why e-mail spending growth will stay moderate in the short term.

"The key reason is cost," said David Hallerman, eMarketer senior analyst. "Because e-mail is a low-cost medium, even relatively large increases in the number of commercial e-mails will not be reflected in large spending increases."

E-mail marketing spending comprises payments to e-mail service providers, list rental and the costs of in-house e-mail. E-mail advertising, on the other hand, is defined as ads running in third-party e-mail newsletters.

eMarketer predicts that US e-mail marketing spending will reach $1.65 billion in 2011, up from nearly $1.5 billion in 2007. In essence, the annual growth rate will slow from 5.6% in 2006 to 1.5% in 2011.

Moderate e-mail marketing spending growth belies actual usage of the tactic. More than seven in 10 marketers surveyed by Datran Media in December 2006 planned to use more e-mail in 2007 than 2006, while only 4.3% said they would reduce their e-mail marketing.

Moreover, nearly every interactive marketer uses e-mail, according to Forrester Research.

E-mail marketers may not need more than one-fifth of a company's e-mail budget to get the job done. More than one-half of US marketers in a March 2007 MarketingSherpa study said that e-mail marketing produced the best ROI of any marketing tactic. Only search engine optimization was more highly regarded for ROI.

Learn why nearly every interactive marketer is an e-mail marketer. Please read eMarketer's E-Mail Marketing: Getting Through to Customers report.