Spark is a great mail client. But "remind me" is not "make sure I do it": a Spark reminder brings a mail back once, and the actual to-do ends up in another app. Gadfly keeps the to-do next to its mail, gives it a deadline, and raises the pressure until it is done.
Good at: A polished, fast IMAP client with Set Aside, snooze and follow-up reminders.
Where it stops: Reminders fire once. To-dos live in Todoist or Notion, not Spark. Lock-screen widgets show mail, not tasks.
Platforms: iOS, Android, Mac, Windows, web. Price: Free; Plus €10/mo.
| Feature | Gadfly | Spark |
|---|---|---|
| Turn an email into a to-do | ✓ Yes | ◐ Partly |
| Every to-do gets a deadline automatically | ✓ Yes | — No |
| Deadline re-read when the thread changes | ✓ Yes | — No |
| Deadline shows the sentence it came from | ✓ Yes | — No |
| Pressure rises as the deadline nears | ✓ Yes | — No |
| Push before a to-do is due | ✓ Yes | ◐ Partly |
| To-dos on the iPhone lock screen | ✓ Yes | — No |
| To-do widget on the home screen | ✓ Yes | — No |
| Starred mail becomes to-dos | ✓ Yes | — No |
| Follow up if no reply | ◔ Coming | ✓ Yes |
| Any IMAP account (iCloud, Fastmail, your domain) | ✓ Yes | ✓ Yes |
| Mail and to-dos in one app | ✓ Yes | ◐ Partly |
| No ads, mail is not the product | ✓ Yes | ✓ Yes |
| Price | €9/mo | Free; Plus €10/mo |
✓ yes · ◐ partly · ◔ coming · ? not documented · — no. From each product's own docs and pricing pages, checked November 2026. Spotted a mistake? Tell us and we fix it.
Pressure that rises until it is done Only in Gadfly Every to-do sits in a band set by its deadline: calm, hot a week out, burning two days out, critical once overdue. As the date nears it climbs, and critical ones break through your quiet hours. Other apps remind you once; Gadfly keeps the pressure on.
Lock screen and home screen widgets Only in Gadfly Your hottest to-dos on the iPhone lock screen and home screen, critical first, plus unread count. Private on a locked phone: band and short title only.
Deadlines that follow the conversation Only in Gadfly When a new message arrives, the deadline is read again from the whole thread. "We will get back to you next week" moves it; a contract expiry stays put. A date you set is never touched.
Every to-do has a deadline Only in Gadfly The date the mail states, else an estimate from what is asked and who is waiting, else a default by importance. No to-do can silently rot without a date.
Deadlines with evidence Only in Gadfly A deadline taken from the mail shows the sentence it came from. No mystery dates.
Gadfly. Like Spark, it is a full mail client, but every email you need to act on becomes a to-do with a deadline read from the mail, and Gadfly keeps the pressure on (bands, nudges, lock-screen widgets) until it is done.
Gadfly Pro is €9/month or €79/year after a 30-day free trial. Spark: Free; Plus €10/mo (checked November 2026).
Yes. Gadfly connects to the accounts you already have: Gmail, Microsoft 365, Outlook.com, iCloud, Fastmail and any IMAP server. Nothing moves; your mail stays with your provider.
Early sign-ups get 3 months of Pro free, not 1.