Designing an email-only Slack interface

← Back to Kevin's homepagePublished: 2018 June 30

On the design of Stop Slacking, which lets you interact via email with the poor souls trapped in the endless, no-agenda meeting that is Slack.

In 2018 May Nicki Vance and I spent a month traveling around New Zealand’s South Island via camper van. Everything you’ve heard about that country’s scenic beauty is true: We traveled forested mountain passes, rolling sheep-filled grasslands, lush rain forests, and pristine glacial lakes:

Camper van in front of lake, with snow-covered mountains in the background

Unsurprisingly, many of these beautiful, remote places had little-or-no cellular connectivity.

The Internet situation was somewhat better in small town hotels and holiday parks, where wifi could usually be had via paper vouchers worth 50 MB or 30 minutes.

This wouldn’t have been an issue if we were 100% on holiday, but Nicki had a part-time retainer doing UX design and strategy consulting with a company in Australia.

Unfortunately, that company communicated almost entirely via Slack.

Slack, for those of you who have only experienced the Internet via direct-fiber-to-San-Francisco, is not exactly a bandwidth-optimized application: Just loading an empty workspace in the web app costs about 8 MB (and that’s before anyone starts posting animated GIFs):

Network tab showing the Slack web app transferring 8 MB just to load an empty channel

This kind of overhead just isn’t going to work when you’ve only got a spotty cellular connection and a bunch of ADHD Aussies incapable of communicating more than one sentence at a time.

If only there were a text-based, asynchronous communication technology robust enough for intermittent, low-bandwidth connectivity.

Say, some kind of technology that downloaded messages when connectivity was available, allowed one to search, organize, and even compose replies while offline, and then send those replies next time connectivity were available.

Product design

As it turns out, a 1970’s technology known as “Electronic Mail” meets all these requirements!

However, it’s no small challenge to convince an organization to switch its preferred communication medium. In this case, it’d be a fight not just against human inertia, but also against hundreds of millions of dollars worth of VC-funded advertising and startup herd mentality.

Together, these two observations form the core product design constraints:

  1. No buy-in. Slackers shouldn’t need to change their behavior at all. The product should provide value to single individuals, without requiring any action from others.

  2. Email only. All interaction should occur over email; sweet, sweet, async, low-bandwidth email. (No web UI, native apps, or talking cylinders.)

These two constraints lead to an ideal product-usage scenario:

To implement this interaction, Stop Slacking must be able to:

We’ll cover these in turn.

Integrating with Slack

Since we can’t require action from a workspace administrator (design constraint #1), a Slack App is off the table.

Fortunately, Slack still supports “legacy” token-based API access, which allows one to programmatically search and post messages via an HTTP API.

Users “sign up” by emailing their workspace token to Stop Slacking then uses this token to poll the Slack API for direct messages and mentions.

Managing emails

When someone receives a message, Stop Slacking sends them an email. When they reply to this email, Stop Slacking posts their reply — so replies must somehow be associated with a Slack message.

Relying on the presence of the original message text is tricky — there’s no reason to expect Slack messages to be unique (e.g., there may be multiple “@non_slacker, do you have a minute?” messages in a channel), so the email would need to include some kind of unique identifier. But that identifier might not make it back in the reply — not all email clients automatically quote emails, they might quote differently, and people might mangle or otherwise remove the identifier.

So, instead of relying on content within the email body, Stop Slacking gives every notification email a unique reply-to address. Then, when an reply is received at this unique address, Stop Slacking knows which Slack message the reply is intended for.

In terms of a person’s email address, there are at least three in play:

This last address cannot be relied upon because of email spoofing, and is ignored entirely.

As for the first two, there’s no reason to constrain them to be identical — in fact, keeping them distinct enables more capabilities.

For example, receiving notifications from different Slack workspaces at different email addresses (say, and allows one to easily tag and filter with their email client.

So, Stop Slacking ignores the email address listed in Slack and instead only uses the one provided with the token during initial signup.

Technical implementation

From a technical perspective, Stop Slacking isn’t a particularly interesting application:

The application state is fairly minimal. It consists of:

The only Slack APIs used are search.messages (to poll for messages) and, which is needed to replace user IDs in message text with display names (presumably, Slack stores references to other Slackers within message text as IDs so that messages can always be rendered with someone’s current display name).

Perhaps more interesting was the coding itself — the application couldn’t be run locally within the camper van itself, because simply retrieving the AWS SDK dependency from Maven would cost 160MB. Instead, the application was developed on a throwaway EC2 development machine via SSH.

Nicki and I designed and built the prototype together over a few evenings in New Zealand. Since then, she’s written and illustrated the landing page and refined the product features.

Future work

While we developed Stop Slacking specifically for Nicki’s situation, there are some features that should easily fit within the current design and provide more powerful capabilities: