E-mail mechanics: Managing domains, subdomains and IP addresses

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Most marketers probably spend a lot more time thinking about messaging than they do about the technical workings of their e-mail marketing program. While messaging is certainly important, how you send your e-mail—and how you use your domains, sub-domains and IP addresses—can definitely affect your deliverability rates, said Dave Lewis, CMO at e-mail messaging firm Message Systems.

For example, a company might make the mistake of sending e-mails for all its lists and different internal divisions from the same domain name as well as the same IP address. Or they might move lists from domain to domain or IP address to IP address; a list that once received e-mails from “” might be moved to “”

“When companies aren’t paying attention to these things, they are leaving their customers open to phishers,” Lewis said. “If the customer doesn’t know which subdomain is actually the one you’re regularly mailing under, they may fall victim to phishing,”he said. “Plus, [the marketer is] taking chances with their own deliverability and e-mail reputation,” he added.

Lewis provided one secret and one lie about e-mail mechanics that can help you avoid just such a fate.

Secret: It’s not necessary to set up a new domain or subdomain every time you set up a new mailing list.
Segregation of mailstreams is important, but you should do so based on business divisions, products or services, not how new a list is, Lewis said. This means if you add a new-product-support newsletter, you can add it to your existing domain (maybe you’ve already got a “” and you’ll use “” to create the segregation). Both lists will take advantage of the reputation the first one has already built, making it easier to get the new list delivered—but it won’t sully the old list’s reputation, Lewis said.

If you’re simply starting a new e-mail marketing list within the same product line, Lewis suggested using the same subdomains but differentiating within the subject line. No matter what, though, it’s important to keep transactional and customer service domains separate, he said. “People think of reputation as IP addresses, but it’s really about the subdomain,” Lewis said. “You want to set up domain and subdomains to reflect how you operate your business. Bottom line: This is a branding issue and a customer service issue.”

Lie: You can improve deliverability by rotating your IP addresses.
Maybe you’ve gotten a few spam complaints with a specific marketing program. What do you do? For many, that answer seems to be move the list to another IP address, Lewis said. “People keep rotating IP addresses, trying to avoid burning a specific IP address out; but this is the wrong strategy,” he said. “What ISPs, carriers and corporate e-mail servers look for is continuity and consistency.”

These entities associate specific domains and subdomains with IP addresses and, when they get swapped out, a red flag goes up, Lewis said. “While the strategy might yield a short-term benefit, ultimately it’s going to lower your deliverability rate.”

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