This holiday season, I've been seeing more and more animated gifs in emails. Everything I've read recommends no more that 400 KB for best practices, and some ESPs say not over 250 KB. I would love to hear what other people are using and any results.

In Theory (based best practices advice):
• Keep your file size under 400 KB.
• Keep your image size under 480 pixels in width and height.
• Keep the number of frames under ten.
• Put your most important frame first, to ensure Outlook 2007 and 2010 users don't miss the message. (Outlook 2007 and 2010 will only display the first frame in an animated GIF)

In Practice (These are some of the file sizes I've seen in competitor's emails.):
Ann Taylor keeps theirs at 400KB or less
America Apparel's are 200 - 700KB
Sephora mostly under 400KB
Brooks Brothers 1.4MB
Bonobos 1.6MB
Smashbox 4.2MB (Seriously!?!)

From what I've read, the large emails should have gotten blocked by some email clients. The risk you run (most likely on mobile phones) is larger sized emails could force email platforms or devices to truncate a message or to block delivery entirely. My fear for my clients would be if their emails get blocked, it might negatively impact the integrity or their email list causing deliverability issues for future emails.

Personally, I have sent animated gifs at 700KB (via Responsys) and 900KB (via Blue Hornet) with no noticeable problems and open rates comparable to smaller emails, so far emails lists have not been negatively impacted.

My question is - How big is too big?

I'd love to hear any feedback and super excited about this Community forum! Thanks Litmus!!