There are three email metrics that almost every B2B sales team still
tracks and almost every B2B sales team should stop trusting in the way
they currently do. The metrics aren't broken; what's broken is how
they're measured.
*1. Open rate
*
The textbook definition: share of delivered emails where the recipient
opened the message. In 2025 and earlier, this was approximately what
was being measured. In 2026 it isn't.
Apple Mail Privacy Protection (MPP), launched with iOS 15 in September
2021, pre-loads every remote image (including tracking pixels) on
Apple-controlled relay servers before the recipient opens the email.
With Apple Mail at roughly 58% global email-client market share
(Litmus), MPP affects half or more of every B2B list.
Corporate email scanners (Microsoft Defender for Office 365, Mimecast,
Proofpoint) pre-fetch every link and image on every email for malware
scanning. Every enterprise B2B prospect generates a fake open within
seconds of delivery.
Gmail's image proxy can register the same pixel as multiple opens.
Smaller problem, still real.
The result: a reported 70% open rate typically maps to a 25-35% actual
human-read rate.
The fix is confidence scoring: grade each open from Tier 1
(high-confidence human) to Tier 5 (bot/scanner) based on IP block,
User-Agent, and timing signature. Filter below a 25% confidence
threshold.
*2. Click-through rate
*
The same problem reaches clicks. Microsoft Safe Links, Mimecast URL
Protect, and Proofpoint TAP pre-fetch every link on every email for
malware scanning. Every link gets clicked automatically by the scanner
within seconds of delivery.
Unfiltered click-through rate in 2026 is contaminated 2-3x by scanner
auto-clicks. The fix is unique-clicks-per-recipient with scanner-IP
filtering and a time-window filter (any click within 5 seconds of
delivery is almost always a scanner, not a human).
*3. Time-to-first-open
*
When the open is a machine pre-fetch firing 30 seconds after delivery,
the average time-to-first-open metric becomes meaningless. The measure
that actually matters is time-to-first-Tier-1-open: when did a real
human first engage with the email?
The structural lesson: 2026 email tracking only works if it filters
MPP, scanner pre-fetches, and proxy duplicates. Tools that count raw
pixel loads are reporting noise, not engagement.
I wrote up the technical breakdown of how MPP actually works here:
https://outsolvi.com/glossary/apple-mail-privacy-protection
- Nate Summers Co-Founder, Outsolvi
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