As the volume of holiday print catalogs threatens to break the backs of America’s postal letter carriers, it would stand to reason that consumers’ e-mail inboxes would be overflowing, as well, and opt-outs would be skyrocketing as a result.

However, mainstream retailers are showing a surprising amount of restraint in their e-mail efforts this season, according to experts.

For example, AOL’s postmaster Charles Stiles said that though the Internet service provider’s network is experiencing a significant spike in e-mail from non-spamming marketers, subscriber complaint rates have not risen accordingly.

“We see absolute huge spikes in [legitimate marketing e-mail] messages coming through,” said Stiles. “But I wouldn’t say that there’s a huge increase in abuse reports, largely because these are, in fact, legitimate marketing messages, and they’re not going to generate that many abuse reports.”

Also, even with the holiday spikes in their outbound e-mail efforts, mainstream merchants account for a relatively small volume of mail hitting AOL’s network, said Stiles.

“Spammers still far outweigh what legitimate marketers send,” he said. “That’s where we see the biggest problem.”

Stiles’ assessment of mainstream marketers’ overall e-mail behavior jibes with that of John Rizzi, chief executive of e-Dialog. According to Rizzi, the e-mail service provider’s retail clients’ outbound e-mail volume is up 40% from September levels, but their opt-out rates have not risen.

“E-mail is maturing, and people are understanding the optimal frequency to mail out, the optimal content and all these other things,“ said Rizzi. “And included in the equation of what’s optimal is how to avoid opt-outs.”

He said that consumers expect more contact from retailers this time of year and, as a result, are more tolerant of increases in e-mail volume than they would be otherwise.

“We’ve also learned what’s effective without being abusive. Consumers do in fact expect more this time of year. They open more because they’re going to spend more,” he said. “It’s a matter of getting it all into balance and maybe this is the best year of balance the industry’s been able to sort out so far.”

Rizzi added that the threat of ISPs blocking e-mail from reaching subscribers has probably also spurred mainstream marketers into treating the medium with more care.

“There has been a certain level of discipline that everyone has learned that it’s not worth crossing the line,” he said. “Good marketers are very concerned about that.”

Rizzi also said that many retailers have taken a lesson from Neiman Marcus, which has come under fire from critics who said the luxury retailer sent its customers too much holiday e-mail.

“It’s almost become folklore in the industry that ‘you don’t want to do a Neiman Marcus,’” he said. “That lesson stands in the marketplace.”

Chip House, vice president of marketing services for e-mail software provider ExactTarget, added that inbox providers have gotten better at processing inbound permission-based e-mail.

“The ISPs seem to me to have drastically improved their infrastructure,” he said. “All of the majors have probably had their times when they’ve struggled a little bit, but all indications are that they’ve made improvements to keep up with the increased volume.”

House also said that, anecdotally, it seems that clients are sending smaller, more targeted campaigns this holiday season.

“I can think of a couple of different clients who are, rather than blasting their entire list with one campaign, are breaking it up over different segments and spreading it out over several days,” said House. “Calmer rational minds are prevailing and most of our larger clients aren’t going to go crazy with their mailings.”

As the volume of holiday print catalogs threatens to break the backs of America