It's no surprise that the majority of the biggest email days come in the weeks before Christmas -- including seven of the top eight. Those days include Cyber Monday (Nov. 27) and all three "Echo Mondays" (Dec. 4, 11 and 18) -- the Mondays that follow Cyber Monday. Interestingly, two of the three Echo Mondays were bigger email days than Cyber Monday, which is billed as the biggest online sales day of the year.

However, the biggest email day of the year was actually the day after Christmas; more than 53% of the retailers tracked via RetailEmail.Blogspot sent email on Dec. 26, 2006. In addition to capturing added sales from returns, this tactic was no doubt used to try to capture gift card and e-gift card sales as quickly as possible.

Besides Christmas, other high-volume email days occurred in connection with tax day (April 17 this year), Thanksgiving, Mother's Day, Father's Day, President's Day, Valentine's Day and Easter.

Here's a listing of the top 20 retail email days:

% of retailers sending email, day, proximity to holidays
53.1% - Dec. 26, 2006, Tuesday, the day after Christmas
49.0% - Dec. 11, 2006, Monday, 14 days before Christmas
45.9% - Dec. 15, 2006, Friday, 10 days before Christmas
44.9% - Dec. 18, 2006, Monday, 7 days before Christmas
43.7% - April 17, 2007, Tuesday, Tax Day
43.7% - Nov. 27, 2006, Monday, the Monday after Thanksgiving Day (Cyber Monday) and 28 days before Christmas
42.1% - Dec. 4, 2006, Monday, 21 days before Christmas
42.1% - Dec. 8, 2006, Friday, 17 days before Christmas
40.2% - April 24, 2007, Tuesday, 19 days before Mother's Day
40.0% - June 5, 2007, Tuesday, 12 days before Father's Day
39.6% - Dec. 1, 2006, Friday, 24 days before Christmas
39.4% - Feb. 20, 2007, Tuesday, the day after President's Day
39.2% - Nov. 14, 2006, Tuesday, 9 days before Thanksgiving Day
38.8% - Jan. 29, 2007, Monday, 16 days before Valentine's Day and 6 days before the Super Bowl
38.4% - June 11, 2007, Monday, 6 days before Father's Day
37.9% - Dec. 7, 2006, Thursday, 18 days before Christmas
37.8% - Dec. 14, 2006, Thursday, 11 days before Christmas
37.8% - Dec. 12, 2006, Tuesday, 13 days before Christmas
36.7% - March, 29, 2007, Thursday, 10 days before Easter
36.7% - Dec. 20, 2006, Wednesday, 5 days before Christmas

Everyone may not immediately think of Tax Day as a great time for retail emails, but when you consider that most people get refunds and that most people wait until the last second to file, tax day emails make sense.

While many of the major holidays each had a spike associated with it, the Valentine's Day spike that made it into the top 20 was unique in that it got a boost of adrenaline from the Super Bowl, which was Feb. 4. Mass merchants and electronics retailers are pushing big-screen TVs ahead of the big game and sporting goods retailers are promoting apparel for the two teams and the eventual winner. Combine that with the ramp-up to Valentine's Day and that's a powerful testosterone-estrogen, one-two punch.

Looking at the months in which these days fall, more than half fell in December, with most of the rest spread thinly over January, February, March and April. The summer months -- July, August and September -- and October, are not represented at all.

Looking at the most popular email days, the day selections support the general finding of my column last week in that Tuesday was the popular day for these volume spikes. Monday was close behind, and far more popular than the remaining days of the work week. There were no major volume spikes on either Saturday or Sunday, in keeping with their general lack of popularity.

With so many of the top 20 email volume spikes occurring in November and December, the timing trends are worth considering as you plan your holiday campaigns.

Chad White is director of retail insights and editor-at-large at the Email Experience Council. Visit his blog at http://retailemail.blogspot.com.

This commentary is insightful. I recommend it to others.