Why do I see a spike in Yahoo! Mail opens?

In July and August of 2018 we identified an issue that caused an increase in Yahoo! Mail open reports in Email Analytics triggered by Yahoo! Mail’s Proxy Server.

What’s Yahoo! Mail’s Proxy?
In March 2018, Yahoo! Mail introduced image caching. Rather than serving images from their original server, Yahoo! started caching all images, and now serves them via their own proxy servers. You can read more about this update on the Litmus Blog.

Increases in email opens triggered by Yahoo! Mail’s proxy server
In Litmus Email Analytics, any opens triggered by Yahoo! Mail’s proxy are recorded as “Yahoo Mail”, “Via Yahoo’s Image Cache“. Beginning around July 13, 2018, we’ve discovered a steep increase in open reports triggered by Yahoo! Mail’s proxy.

On or around this date, Yahoo! and AOL merged their backend infrastructures. As part of this merger two things happened:
– Both Yahoo! and AOL opens are now processed by the same Yahoo! Proxy server
– Yahoo! made a subtle change to their proxy server that caused it to retry Litmus’ Email Analytics tracking pixel up to 4 times, resulting in an increase in open reports for Yahoo! Mail

We have fixed the way we record these opens, so they will no longer be inflated. However, since both Yahoo! Mail and AOL are now processed by the same backend servers, we can no longer distinguish between them. That’s why both AOL and Yahoo! opens will report as Yahoo!/AOL going forward.

The net result of these changes are:

– Opens on AOL and Yahoo! Mail from July 13 to August 8 will be reported as Yahoo! and will likely be 4 times larger than normal. For example if you had 3 Yahoo! opens and 2 AOL opens in this window that would report as 20 Yahoo! Opens (3 + 2 = 5 real opens, 5*4 = 20). Only opens in that window are affected by this.
– Going forward, all Yahoo! and AOL opens will be reported as Yahoo/ AOL.

If you have any questions, please don’t hesitate to reach out to hello@litmus.com.

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