Our company places an email tracking image in our outbound marketing emails to track how many people are reading our messages. Around 11/20/2021, give or take a few days, we started seeing a steep increase in the number of requests for this image from various IP addresses that map to the Cloudflare ASN. The increase leveled off by 12/20/2021, and has remained at a new, much higher baseline - approximately 2x higher than it was before the increase began.
We do not believe that this represents an influx of new customers or an increase in the amount of actual people reading our emails. We are trying to determine if perhaps any new features have been launched in the past year that might cause the images in customers’ emails to be preloaded over Cloudflare before they have actually read their email.
So far we have come across a couple of possibilities:
- Cloudflare Email Routing: https://blog.cloudflare.com/introducing-email-routing/
- iCloud Private Relay: https://blog.cloudflare.com/icloud-private-relay/
However, I don’t see anything that would indicate that these services would cause images in emails to be preloaded.