You sent a proposal three days ago. Nothing back. The question eating at you: did they even see it?
There are ways to find out. Some of them are fine. Some of them are... not great. The line between "professional follow-up" and "I'm watching you" is thinner than you'd think, and I've seen people cross it without realizing.
Where the line is
There's a simple test I use: am I tracking my own performance, or am I tracking their behavior?
"My proposal hasn't gotten a reply in 5 days, I should follow up." That's fine. That's just managing your pipeline.
"They opened my email 7 times at 11 PM from their phone in Brooklyn." That's surveillance. Even if the tool lets you see that data, using it to time your follow-up is... weird. Don't be that person.
What's worth tracking
Reply status, did they respond? This is the most important thing and the least invasive to check. It's just looking at your own inbox.
Open count, was the email opened? Useful as a rough signal. If someone opened your proposal four times, they're probably interested but stuck on something. If it was never opened, maybe it went to spam.
Time elapsed, how many days since you sent it? This is really just a calendar question, but having it calculated for you makes follow-up timing easier.
What I don't track: IP addresses, device types, exact open timestamps, forwarding behavior. None of that helps me write a better follow-up, and it feels intrusive.
Reply detection is the workhorse
The most reliable form of tracking is also the least creepy. Reply detection just checks: did a reply show up in the email thread? No pixels, no tracking codes, just looking at whether the conversation continued.
This is the main thing Pynglo does. It checks your Gmail threads for replies and updates your dashboard. Simple.
Open tracking, honestly
Open tracking embeds a tiny invisible image in the email. When the recipient's email client loads images, it fetches the pixel from a server, and that gets recorded.
The truth is it's not super reliable anymore. Apple Mail blocks tracking pixels by default. Gmail proxies images, which throws off counts. Corporate email filters sometimes strip them entirely. I'd treat open data as a hint, not a fact.
Pynglo includes open tracking on follow-up emails but doesn't track IP addresses or location, just whether the email was opened and roughly how many times. I wanted to build something I'd feel okay being on the receiving end of.
When to follow up (regardless of open data)
I used to overthink this. Now I just go by days elapsed:
Day 1-3, leave it alone. Day 3-5, send a gentle nudge if nothing's come back. Day 7-10, ask directly for a decision. Day 14+, send a closing email and move on.
This works whether or not you know they opened the email. You're following up based on reasonable timing, not because you saw them open it at 2 AM. (Even if you did see that, pretend you didn't. I wrote more about what email opens actually mean if you're curious.)
If you're sending proposals and invoices regularly and want a simple way to see who owes you a reply, Pynglo does that without any of the creepy stuff. No location tracking, no device fingerprinting. Just a dashboard with your conversations sorted by status.