Full disclosure up front: we make Sieve, so judge accordingly. Everything below about Mailstrom sticks to its own public positioning.
What is Mailstrom?
Mailstrom's own line is that it's the simplest way to clean up your inbox: it groups your existing mail into bundles (by sender, subject, or list) so you can keep what matters and delete, archive, or move the rest in bulk, staying in control of every action. Its pricing page promises unlimited email removal on every plan, alongside named tools like Chill, Expire, and Block.
Its FAQ pushes past the one-time purge: your mail is loaded continuously, and rules can automatically act on incoming messages that match your instructions.
What Mailstrom does well
- Bundling is the right primitive for a purge. Grouping by sender or list turns an unmanageable pile into a short list of decisions, and you approve each one: nothing happens behind your back.
- It carries your decisions forward, per its FAQ: mail keeps loading continuously, and rules can apply an action you've chosen to matching incoming messages automatically.
- It scales to many addresses: per its pricing page, Plus covers 3 email addresses and Pro covers 20, with unlimited email removal on every plan.
Mailstrom pricing
As of July 2026, Mailstrom's pricing page lists three plans: Basic at $9 a month or $59.95 a year (one email address), Plus at $14 a month or $99.95 a year (three addresses), and Pro at $29.95 a month or $199.95 a year (twenty addresses). Every plan includes unlimited email removal and starts with a free trial; the tiers differ mainly in how many addresses you clean. Sieve, for comparison, is $10 a month for Basic or $20 for Pro, which adds a second inbox; both are 15% off yearly with a 7-day free trial.
Where Sieve fits differently
Sieve ships with its judgment built in and learns yours as you go. Every incoming message is classified server-side within seconds. Cold outreach goes under a Solicitor label, phishing under Malicious, and both are archived out of your inbox rather than deleted. When it gets one wrong, drag the message back; the correction is recorded automatically and future classifications improve. Reply to someone and Sieve treats them as a trusted sender from then on. And you can steer it in plain English: "I'm not interested in recruiter pitches."
Sieve starts where rules leave off. A rule repeats a judgment you've already made: this sender, this list, this action. Sieve supplies the first judgment itself, on senders you've never ruled on, so the inbox you dug out with Mailstrom stays clean without you writing the rulebook.
Mail from people you already know (your domain, trusted senders, anyone in a thread with you) is cleared by deterministic rules before any AI runs, so its contents are never read by the model. Sieve stores no message bodies (mostly metadata, plus the subject line of flagged mail, encrypted and deleted after 30 days), and nothing is used to train models. Google's security review is complete, and SOC 2 Type II is in progress. Read the Privacy Policy.
Sieve and Mailstrom, side by side
Statements about Mailstrom reflect its own public positioning as of July 2026. Check mailstrom.co for current features and pricing.
When Mailstrom is the better choice
Pick Mailstrom over Sieve if:
- You need a one-time dig-out of an overflowing inbox. Sieve never touches mail that arrived before you connected it: its job is keeping the inbox clean from here on.
- You're not on Gmail or Outlook. Sieve supports those two providers through their direct APIs. It does not support Yahoo or custom IMAP.
- You're cleaning many addresses at once. Its Pro plan covers 20 email addresses for $29.95 a month, per its pricing page; Sieve covers at most two inboxes (the second comes with its $20 Pro plan).