How to Track Email Follow-Ups: The Waiting Column Method

The emails you’re most likely to drop aren’t the ones in your inbox. They’re the ones you sent. You ask a client for sign-off or a colleague for the numbers, and the moment you hit send the thread leaves your screen. Your inbox is a list of what other people want from you. Nothing in it shows what you’re waiting on from them.

This guide covers why follow-ups slip, where the popular reminder tools fall short, and the low-tech system we think works best: a Waiting column, reviewed once a week.

Sent mail is out of sight by design

The Sent folder is an archive, not a to-do list. It mixes the one email that needs an answer with the forty that don’t, and nobody browses it for fun. So remembering what’s outstanding falls to your head, which is bad at it.

GTD’s name for this is an open loop: a commitment your brain is still holding because it hasn’t been parked somewhere you trust. In a series of experiments, psychologists E.J. Masicampo and Roy Baumeister found that unfinished goals caused intrusive thoughts and worse performance on unrelated tasks, and that making a specific plan for the goal eliminated those effects. You don’t have to finish the thing to stop thinking about it. You have to decide what happens next, and when. For a follow-up, that’s simple: check whether they replied, on a day you choose.

The original Waiting For list

David Allen’s Getting Things Done (2001, revised 2015) gives “Waiting For” its own list: everything you’ve delegated, requested or ordered and expect back from someone else. The official GTD blog calls it one of the key buckets in the system and states the email problem bluntly: “So what’s the biggest creator of Waiting For? Sent emails.”

The list only works because of the weekly review, which Allen calls the “critical success factor” of the whole method, and which is the part most people skip. A Waiting For list you never look at is just a tidier Sent folder. (We compare GTD with the other popular systems in email triage methods compared.)

Your options, honestly compared

Gmail’s nudges

Gmail has offered nudges since May 2018. With “Suggest emails to follow up on” switched on (Settings, See all settings, General, Nudges), sent messages that haven’t had a reply get bumped back to the top of your inbox with a prompt along the lines of “Sent 5 days ago. Follow up?”

It’s free and needs no setup. The catch is that Gmail chooses which messages get a nudge and when. You can’t say “this one, on Thursday”, and there’s no view of everything outstanding. Treat it as a safety net.

Outlook flags and reminders

Classic Outlook has the strongest built-in option. Before sending, you can add a follow-up flag for yourself (and optionally one for the recipients) with a custom date, and a reminder comes with it by default.

New Outlook is thinner. Its flag menu offers Today, Tomorrow, This week, Next week and No date, with no custom date. On a Microsoft-hosted account, flagged mail also appears in Microsoft To Do, where you can add a due date and reminder, though now your follow-ups live in a second app.

Neither version notices replies: a flag stays up, and the reminder fires, whether or not anyone has answered. (More in how to organise your Outlook inbox.)

Boomerang

Boomerang is the best-known add-on, and it combines the two things you want: a reminder at a time you pick, which only fires if nobody has replied. It runs as a browser extension for Gmail, and there’s a version for Outlook 2021 and later, Outlook for Mac and Outlook on the web.

The free Basic plan gives you 10 message credits a month; unlimited use starts at $4.98 a month billed annually. Boomerang says it stores message headers but not bodies and has annual SOC 2 Type II audits. It still needs OAuth access to your mailbox, which is worth granting deliberately rather than clicking through.

FollowUpThen

FollowUpThen needs no install at all. You add an address like 3days@fut.io to an email. In BCC, only you get the reminder; in CC, everyone in the To field gets a follow-up when it’s due. It works from any client on any device, which is its great strength.

It’s free for up to 50 active reminders a month, then $4 a month. By default it reminds you whether or not they’ve replied; cancelling on reply is a paid “Response Detection” add-on that needs you to connect your inbox (headers only). And because you’re sending it a copy, FollowUpThen stores the message, encrypted, for between four weeks and six months after the follow-up fires, or deletes it straight away in privacy mode.

BCC yourself

The zero-cost version: BCC your own address on anything you’re waiting on, then file the copy that lands in your inbox into a Waiting folder or label. The GTD blog suggested a slicker variant back in 2009, a rule that files a copy of any sent email containing a keyword like *wf* into a Waiting For folder. Either way you get a list but no reminder. You still have to go and look.

Calendar reminders

For the few follow-ups that really matter, such as a contract or a late invoice, a calendar entry is hard to beat: it fires when you chose, on every device you own. It just doesn’t scale. Add fifteen “chase Sam” events a week and you’ll start dismissing them all, and the calendar has no idea whether Sam already replied.

A Waiting column

The last option is a place rather than a reminder: a folder or label called Waiting, ideally visible next to your inbox rather than buried in a sidebar. It’s GTD’s list, kept inside your email where the evidence already is. It costs nothing and works with any provider, but like every list, it never pings you. It only works with a review habit, which is what the rest of this guide is about.

The Waiting column method

What goes in it

Anything where the next move is someone else’s and you’d mind if it never happened:

• questions you’ve asked that block your own work
• approvals, sign-offs and decisions
• documents, quotes or figures someone promised
• orders, refunds and bookings awaiting confirmation
• anything you’ve delegated

What stays out: FYI emails, threads where you’d be happy never to hear back, and things you owe other people, which belong in To Do. If Waiting holds only other people’s moves, one glance tells you who owes you what. Our kanban for email guide covers the rest of the board.

The rule that makes it work: move the thread into Waiting the moment you send, before you open the next email. Later means never.

A 15-minute weekly review

Pick a slot you’ll keep. Thursday or Friday morning works well: late enough to know what’s stuck, early enough that people can still answer before the weekend. Then go through each thread:

1. Did it come back? Move it to wherever the next action lives, or archive it if the reply settles the matter.
2. Is it overdue? Chase it now, during the review. A follow-up takes two minutes to write, and putting it off defeats the point.
3. Not due yet? Leave it. Seeing it and deciding not to act is the review working.
4. Chased twice already? Switch channel, escalate or close it (see below).

Finish by scanning the last week of your Sent folder for anything that should be in Waiting but isn’t. That catches GTD’s “biggest creator” once a week instead of never.

If the review regularly takes longer than fifteen minutes, the column is holding things that belong somewhere else.

When to chase

Replies tend to come fast or not at all. In a 2015 study of more than 2 million Yahoo Mail users, researchers from Yahoo Labs and the University of Southern California found the most likely reply time was two minutes, half of replies arrived within 47 minutes, and more than 90% within a day. Emails received at night or at the weekend got slower replies. The reply-time analysis covered pairs of people who regularly email each other, which is roughly your situation when chasing a colleague.

Vendor data points the same way, with the caveat that it comes from a company selling follow-up tools. Yesware analysed over 500,000 sales emails sent by its users and found 90% of replies came within a day of the email being opened, and that an unanswered first email still had a 21% chance of a reply to the second. That’s cold sales outreach, not your colleague’s inbox, but the shape matches.

Neither dataset is new, and neither can count the replies that never came. But once a day or two has passed, you’re in the long tail, and a polite nudge will likely do more than more waiting. Our rough defaults:

• Blocking or time-sensitive: one working day.
• Normal work requests: three working days.
• Low-stakes, external or “whenever you get a chance”: a week.

If the original email gave a deadline, that’s the chase date. And adjust for the person. Some people answer within the hour, some clear their inbox on Fridays, and you’ll soon learn which is which.

How to write a follow-up that isn’t passive-aggressive

The aim is to make replying easier than ignoring you. We’ve written a whole post on the phrases that make work email sound passive-aggressive, so here’s the short version:

• Reply in the same thread, so the context is right there.
• Assume good faith. “In case this got buried” lands far better than “per my last email”.
• Restate the ask in one line. Don’t make them scroll to find it.
• Make it easy to answer, with a yes-or-no question or a default you’ll act on if you don’t hear back.
• Keep it short. A 2016 Boomerang analysis found emails of 50 to 125 words did best, and that asking one to three questions made a response 50% more likely than asking none. It’s one vendor’s correlational data, but it matches common sense.
• Don’t mention that you can see they opened it. Read tracking is a conversation nobody enjoys.

Something like:

Hi Sam, bumping this in case it got buried. I need sign-off on the brochure copy to book the printer by Thursday. Is the version I sent on the 3rd good to go? If I don’t hear by Wednesday, I’ll send it as is.

When to give up and close the loop

Two follow-ups by email is usually enough. After that, email isn’t working, so change something:

• Switch channel. A two-line chat message or a phone call often clears in minutes what three emails couldn’t.
• Escalate, if it’s genuinely blocking you, by asking someone else who can answer, with the original person copied in.
• Close it. Send one last friendly note (“I’ll assume this isn’t a priority right now and take it off my list. Just reply here if that changes.”), then archive the thread.

Closing a loop on purpose isn’t failure. A Waiting column full of things you’ve quietly given up on is one you stop trusting, and then stop checking. The archived thread is still searchable, and if they do reply, it lands back in your inbox. (If an overflowing column makes you anxious rather than organised, that’s a different problem, covered in unread email anxiety.)

Doing this in Kanmail

Full disclosure: this is our client. Kanmail lays your email out as a kanban board where columns are your folders or Gmail labels, so the Waiting column is a real folder on your mail server, sitting next to your inbox. A few details help with follow-ups:

• Reply from the card with r, then drag the card to Waiting, or press m and pick Waiting. Either way the thread is re-filed on the server.
• Kanmail groups messages into conversations using the standard reply headers and includes your Sent folder, so the Waiting card shows your reply alongside the message you were answering.
• When they reply, the new message arrives in your inbox on the server, but Kanmail shows it on the existing Waiting card rather than as a separate inbox card. The card jumps to the top of the column and shows as unread, so your review starts with what came back. (This relies on their mail client keeping the reply headers, which nearly all do.)
• Archiving the card with Enter archives the whole conversation, including that reply in your inbox.
• For a brand-new email that isn’t a reply, BCC yourself and drag the copy to Waiting when it arrives. You can also add Sent as a column and drag from there, though that moves the message out of your Sent folder.

The honest trade-off: Kanmail has no reminders or snooze. The Waiting column shows everything outstanding, but it won’t tap you on the shoulder, so the weekly review has to do that job. If you want a ping as well, add calendar entries for the few follow-ups that really matter, or put FollowUpThen in BCC. And there’s no mobile app, so the review happens at your desk.

The bottom line

Follow-ups slip because the thing you’re waiting on disappears the moment you send it. Every fix here works by putting it back in view, whether that’s automatic (Gmail’s nudges, Boomerang), on a date (Outlook flags, your calendar) or on a schedule you control (a Waiting column).

Pick the one you’ll actually look at. For most people that’s a Waiting column, fifteen minutes each week, and a simple chase rule: one working day for urgent, three for normal, a week for everything else. If you’d like that column on a board next to your inbox, Kanmail is free to evaluate for as long as you need.