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Slashy embeds an invisible tracking pixel in outgoing emails so you know when a recipient opens your message.
Email tracking is not 100% reliable. Privacy features in Apple Mail, corporate firewalls, and image-blocking settings can prevent tracking pixels from firing. Treat open data as a signal, not a certainty.

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How It Works

When tracking is enabled, each outgoing email gets a tiny invisible image per recipient. When the recipient’s email client loads images, Slashy records:
  • Exact timestamp
  • Device type and OS
  • Email client
Tracking is per-recipient — if you send to three people, you see exactly who opened.
Email tracking panel showing open timestamps, device info, and recipient details

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Tracking on Your Sent Emails

Open tracking is on by default for the emails you send. Slashy adds the invisible image to each outgoing message and records opens per recipient. There is no in-app switch to turn it off; if you would rather not track opens, email founders@slashy.com and we will turn it off for your account.

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Viewing Open Data

Press d o to open the Recent Opens panel — a live feed of who’s reading your tracked emails. Each entry shows: recipient name, email subject, time opened, device type, OS, and email client. You can also view tracking data on individual threads — sent messages show an “Opened by” indicator. On mobile, the read receipt sheet shows each recipient with their contact avatar next to their open status, so it’s easy to scan who has and hasn’t opened at a glance.

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When Tracking Doesn’t Work

If a recipient replies to a tracked email but the pixel never fired, Slashy still shows the message as opened, labeled “Opened. Privacy protection likely blocked tracking.” so you’re not left guessing why the open count reads zero on a message you clearly got a reply to.

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Private Reading for Emails You Receive

Tracking works both ways: many senders put hidden tracking pixels in the mail they send you, so they know when you open it. Private reading blocks those.
1

Open Settings

Press Cmd+, and go to Account.
2

Turn on Private reading

Find Private reading in the Compose & Reply group and switch it on. You can also press Cmd+K and search “private reading”.
Settings, Account, Compose & Reply group with the Private reading toggle
With Private reading on, other senders’ hidden tracking pixels are blocked, so their open receipts never fire. The images a sender meant you to see, such as logos and photos, still load normally, and there is nothing to click to reveal them. Read receipts between Slashy users keep working, and the emails you send are still tracked. Private reading is off until you turn it on, and it applies to every connected account. Embedded videos such as Loom wait behind a Load Loom video button while it is on.

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Team Read Receipts

If a teammate CCs you on an email they sent with tracking on, you see the same open data they do, right on the thread. There’s nothing to set up: as soon as you’re on a tracked message together, opens show for both of you. See Team management to invite teammates.

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Auto-Open Filtering

Slashy filters automated opens from Gmail Image Proxy, Apple MPP, Microsoft SafeLinks, and corporate security scanners. You may miss occasional real opens, but the ones you see are genuine.

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Open Trigger Automations

Create automations that fire when a tracked email is opened — for example, get notified when a prospect opens your proposal.
1

Open the agent sidebar

Press Cmd+/ or d a.
2

Ask the agent to create an open trigger

Example: “Create an email open trigger: when anyone at @bigclient.com opens my email for the first time, message me on iMessage.”
3

Define your condition and action

The agent shows a preview of the trigger for your confirmation. Adjust the scope or action as needed.
Open triggers include the same auto-open filtering and can fire on first open only or every open.
Combine email tracking with the Follow-Up Nudge automation for a powerful outreach workflow: track opens, then auto-draft a follow-up if the recipient opens but doesn’t reply within 3 days.

10 Automations

Set up email open alerts and more

Never Miss a Follow-up

Four layers of follow-up protection

Slashy for Sales

Sales workflows using tracking and follow-ups

Customer Follow-ups

Automated follow-up tracking for key accounts

Security and privacy

What Slashy can and cannot do with your mail