Cold email open rates: why the number misleads you

People ask me what a good cold email open rate is, and I understand why: it's the first number every tool shows. My honest answer is that it's the least reliable number on the screen. It can still tell you something, as long as you know what it can't.

What an "open" actually records

An open is a tiny image being fetched, not a person reading. Apple Mail can fetch that image by itself as soon as the email arrives. Security filters at larger companies can fetch it too while checking the message. Meanwhile, a real reader whose mail program blocks images never counts. Here's how tracking works in more detail.

Why published benchmarks don't help

You'll find plenty of articles quoting an "average" open rate. I wouldn't plan around any of them. The figure depends heavily on how many of your recipients use Apple Mail, which tool counted it, and whether automatic opens were removed. A 70% from one tool and a 40% from another may describe the same campaign.

What an open rate can still tell you

Compare a campaign with itself, not with the internet:

• A sudden drop across every mailbox suggests a deliverability problem. Check it with a placement test before you touch the copy.
• A drop on one domain or mailbox only points at that domain or mailbox. Rest it and check its DNS and blacklist status.
• A subject line A/B test on the same list, in the same week, can give you a rough lean. Treat small differences as noise.

The numbers I judge a campaign by

• Reply rate. Over 6+ years and roughly 12 million emails, I've mostly seen 1-3%. See what counts as a good reply rate.
• Interested replies. Ten "yes, tell me more" beat fifty "please remove me".
• Meetings and customers. This is what the whole thing is for.
• Bounce rate. Keep it under 2%. Above that, stop and clean the list.
• Spam complaints. Gmail's line is 0.3%, and you want to stay under 0.1%.

Low opens: what to check, in order

1. Authentication: check SPF, DKIM and DMARC on the sending domain.
2. Placement: run a test to see whether you're landing in spam.
3. Volume: about 30 campaign emails a day per mailbox is where I'd stay.
4. List quality: old or unverified lists bring bounces, and bounces hurt everything else.
5. Subject line: only now, because a better subject can't rescue an email in the spam folder.

mailzy shows Apple's automatic opens separately so they don't inflate your figures, and lets you run a placement test before launch. See analytics.