Promotional e-mails sent by retailers were slowly increasing throughout 2008. The largest numbers came in at the end of the year in December with 14.6 e-mails sent on average to consumers, doubtlessly due to the holiday season and recession.
As you can see below, the majority of consumers e-mail grew during the 2008 holiday season
Note: *November 8-December 19 2008
Source: eMarketer, February 23 2009