Best AI email assistants: how to choose

The short answer

The right AI email assistant depends on three things: which email provider you use, how much you want it to do without asking, and whether you want a new app or a layer on the one you have. If you use Gmail only, Shortwave and Gmail's own Gemini features are built for it. If you use Outlook or both, check provider support first, because it removes options faster than any feature does. If you want an assistant that prepares work and stops for your approval, that is the line Otto draws.

Disclosure. Otto is our product. This list is not paid placement and has no affiliate links. We read each product's own pages on 9 October 2026 and did not run a head-to-head test. Plans and features change, so each entry links to its source.

How we compared them

Six questions, in the order they usually decide a choice:

1. What can it change without asking? Drafts only, or can it send, archive and delete?
2. Which providers does it support? Gmail only, Gmail and Outlook, or any client.
3. What does it read and keep? Message bodies, or only headers?
4. What is the cost shape? Free plan, trial, per seat, usage credits.
5. Which platforms? Web, iPhone, Android, Mac, Windows.
6. What job does it do? A new mail app, a layer on your app, or an assistant.

We left out any claim we could not find on the product's own pages. A price appears only where the vendor's own page states it in US dollars.

The eight

Otto

Gmail and Outlook in one app with calendar, tasks and an assistant that drafts, finds, books and files. Anything that sends, books or changes waits for your approval, and automatic replies only run inside limits you set. Free covers one connected account; Plus is $6.99 a month and Pro is $19.99 a month. It runs on the web and on iPhone.

Suits: people on Gmail, Outlook or both who want mail, calendar and tasks together. Limit: no native Mac or Windows app, and no meeting recording. Alternatives pages say more.

Superhuman Mail

A shortcut-first client that says it is built for teams that use Gmail or Outlook. Its Mail page lists Split Inbox, follow-up reminders, Send Later, snippets, read statuses and shared views. It describes AI that drafts and, if you want, sends for you. As of October 2026 its plans page lists Mail on the Business and Enterprise plans.

Suits: people whose day lives in the inbox and who want speed. Limit: no free Mail plan on the page we read. See Superhuman alternatives.

Shortwave

An AI mail client for Gmail, with AI search, AI filters, bundles, delivery schedules and a free plan. Its docs say Microsoft 365 and Exchange accounts are not supported at this time. Apps for Mac, Windows, iOS and Android.

Suits: Gmail and Google Workspace users who want AI inside the inbox. Limit: Outlook is out. See Shortwave alternatives.

Spark

A mail client whose Free plan lists a Smart Inbox, unlimited accounts and a calendar. AI features and team tools sit on paid plans, and its pricing page marks Autopilot and Auto-Drafts as coming soon. Apps for Mac, Windows, iOS and Android.

Suits: people with many accounts who want a good free client. Limit: the AI is on paid plans. See Spark alternatives.

Fyxer

Works inside Gmail and Outlook. It drafts replies in your tone, labels mail and records meetings for notes. Its pricing page says it drafts and you decide what is sent, and describes monthly credits.

Suits: people whose week is email plus meetings. Limit: credit-based usage, and it is an add-on rather than a mail app. See Fyxer alternatives.

SaneBox

Works with every email client. It filters unimportant mail, offers BlackHole for unwanted senders, a Daily Digest, follow-up reminders and snooze, and says it looks at sender, subject and date and does not store full emails or attachments.

Suits: people happy in their current client who want it quieter. Limit: it sorts mail; it does not write replies. See SaneBox alternatives.

Gmail with Gemini

Google's own AI inside Gmail, including thread summaries and Help me write. Which features you get depends on your plan, language and region, and Google lists the current availability in its Gemini in Gmail help page.

Suits: people already in Gmail who want no new app. Limit: Gmail only, and eligibility varies.

Outlook with Copilot

Microsoft's Copilot in Outlook can prioritize your inbox, summarize a thread, draft with Copilot and coach on tone, according to Microsoft's FAQ. Some features need a Copilot license.

Suits: Microsoft 365 organizations. Limit: license and client dependent.

What they cost

Otto Free costs nothing. These are the lowest paid plans, in USD on monthly billing, from each vendor's own pricing page.

Product	Lowest paid plan	Price	Notes
Otto	Plus	from $6.99/month	Pro $19.99/month; $55.99/year for Plus
Fyxer	Pro	from $49/month	per seat, $37/month billed yearly
Shortwave	Business	from $30/month	per seat
Spark	Plus	from $10/month	per seat, $8.25/month billed yearly
SaneBox	Snack	from $3.49/month	filtering for your current mail app, $2.42/month billed yearly

Superhuman's price depends on your region, and Gmail with Gemini and Outlook with Copilot depend on your plan or license, so we list no figure for them. Yearly billing is cheaper where a vendor offers it.

Which to pick

• You use only Gmail and want AI in the inbox: Shortwave, or Gmail with Gemini if no new app is the point.
• You use Outlook or Microsoft 365: Outlook with Copilot if licensed, or Otto, Superhuman or Spark. Shortwave is out.
• You use both Gmail and Outlook: Otto, Superhuman or Spark.
• You want a free client with many accounts: Spark.
• You like your client and want it calmer: SaneBox, or filters and rules from Gmail and Outlook.
• Meetings eat your week: Fyxer.
• You want to approve every send, booking and change: Otto.

Whichever you choose, run one real week through it. A side-by-side comparison can narrow the field and a trial tells you the rest.