It seems that the email client statistics are adding up only to the total number of unique opens, which isn't what the documentation says (and not what is really interesting either).
I'm seeing a 25% iPhone usage, and I thought it was because people would check mail on the iPhone during the day, and then view it on their desktop later, but when I add up the numbers from the email client stats they equal the unique number of opens - not the total number?
If a subscriber was doing what you suggested (opening in their iPhone then in some other email client on arriving home), then provided we can actually register an open, the totals of all the email clients should be more than the total number of unique opens. It will only be equal if those subsequent opens aren't actually viewing the images in the email. If you've got an iPhone it would be easy enough to test exactly that.
If you're convinced the numbers are wrong, perhaps contact support and we can take a peek at the specifics of your case.
Well, what you're saying is that even though I have something like 2x total opens of the unique opens, somehow all extra opens were magically without images enabled? Would you believe that? :o)
I'll get some numbers and take it to support.
ha ha, you're right, i wouldn't believe that :)
What i told you was what i thought it should be, and i immediately confirmed it from the stats on a couple of recent Campaign Monitor newsletters. In each case, the total of the email client numbers is more than the unique opens (from the report snapshot), and that's because a single subscriber opening in two different clients appears twice in the email client report, but only counts as one unique open.
There is one other point of confusion. If someone clicks on a link (but had images disabled the whole time), we will record an open against that person, but because they didn't download the images they don't even appear in the numbers in the email client report. That means that it's possible that clicks could swell the total unique opens to even be more than the total of email clients.
To put some actually numbers on it, let's say you sent your campaign to 5000 people. Of that, you have 2000 unique opens. You go to the email client report, and total up all the numbers, and they come to 2200. The 200 extra come because
1. 200 people opened in two different email clients
2. 100 people opened in two different email clients and 50 opened it in three
3. Actually there were 400 people who opened the mail in two different clients. There were however an additional 200 people who clicked (but never downloaded the images). Those numbers are more complicated, but they do work :P
4. Some other combination of the above
These statistics are always complicated, and it's often not as clean as we want it to be. But if you think your campaign doesn't fit with what i've said, do contact support and we'll have a look.