The main problem is that everyone is upping frequency, so that alone may not be enough to break through.
"Your signal will fade simply because everyone else is also ramping up messages."
"I would encourage folks to watch their spam complaints and unsubscribe rates closely during the holidays and perhaps send fewer emails to their less engaged subscribers."
"A purchase can trigger an email asking the customer to rate or review the product. Then, come holiday time, you can send a top rated products promo email."
"Segment on past purchase behavior, consumer type (high vs. low value), click behavior, location, etc."
"...increasingly, segmentation and targeting are the keys to standing out. We talk all the time about how important relevancy is, but it's even more important when your inbox is suddenly getting 50% more mail."
Everyone offers free shipping around the holidays, so offer something more to your email subscribers to reward them for their loyalty and to encourage list growth.