Mail

Folders

On the left are Inbox, Reminders, Archive, Sent and Drafts. The inbox is shared across all your mailboxes. If you have more than one mailbox, you can show just one.

Triage

Mail is triaged one thread at a time: read, decide, next. These keys work on the selected thread (the full list is in Keyboard shortcuts):

Key	Action
E or Backspace	Archive
# or Delete	Delete
Z	Snooze
P	Remind me (in an hour)
S	Report spam
U	Mark as unread
⌘ Z	Undo the last action

You can undo any action for a few seconds with the Undo button in the notice at the bottom.

Snooze and reminders

• Snooze hides a thread from the inbox and brings it back at the time you pick: In an hour, Tomorrow or Next Monday. Set the morning hour for “tomorrow” and “Monday” in Settings → Mail preferences → Morning hour for snooze. With AI there’s also Smart snooze ✨.
• Remind me moves the thread to the Reminders folder and notifies you at the chosen time (same options). In the Reminders folder the button becomes Done — return to inbox.

On the iPhone the options are In an hour, Tomorrow morning and Next week.

Thread toolbar

Above an open thread there’s a toolbar with the most common actions. Less common ones are under ⋯ (More actions):

• Archive (in Archive: Move to inbox)
• Delete
• Snooze — a menu of times
• Task — Create task from email, Task for a goal… and finding tasks in the text (with AI: Extract tasks ✨)
• Reply — the arrow next to it offers Reply all and Forward
• Spam, Remind me, Mark as unread
• Summarize thread — only with AI turned on

Drag an e-mail into tasks

On the desktop and in the web version you can grab a message in the list with the mouse and drop it:

• on the Today at a glance panel on the right — it becomes a task for today (Today column, due today),
• on Tasks in the top bar — it becomes a task in the Inbox.

While you drag, the places you can drop on light up with a short label (e.g. Drop = task for today). The task takes the e-mail’s text, a link back to it and its attachments; the message stays in your mail. After the drop a confirmation offers Open task and Undo (which deletes the task again). If you already have a task from that message, no second one is created — Letos offers to open the existing one.

Writing and sending

• Start a new message with C or ⌘ N, send with ⌘ Enter.
• Undo send: after sending you have a moment to Undo. Set the length in Settings → Mail preferences → Undo-send window (default 10 seconds, 0 = send immediately).
• Send later: In an hour, This evening, Tomorrow, Next Monday or Custom time…. You can cancel scheduled messages until they’re sent.
• Unsent messages: when a message doesn’t go out, Letos tells you, and in Unsent and scheduled messages you can Try again or Discard it.
• Set a signature per mailbox in Settings → Signatures.
• If you paste a mailto: link into a recipient field, Letos keeps just the address.

Send-as addresses (aliases)

You can send from several addresses through one mailbox, if you have access to them (for example a company address that lands in your mailbox). Set them up in the desktop app under Settings → Email accounts: click Edit on a mailbox and you’ll find the Send-as aliases section in the dialog.

1. Enter the Alias address, optionally an Alias display name (optional), and click Add alias. The alias appears in the list as Not verified; you can’t send from an unverified alias.
2. Click Verify next to the alias. Letos emails a verification code to that address; the code is valid for 15 minutes.
3. Enter the Verification code from the email and click Confirm. The alias then shows Verified. You can send the code again (Send again).
4. You can Remove an alias at any time.

In the compose window you then choose in the From field which address the message goes out from (an alias is marked “(alias)”). Each alias can have its own signature: pick it in Settings → Signatures in the list at the top (that tab only sets the signature; adding and verifying an alias is under Email accounts). An alias without its own signature uses the mailbox’s signature.

Aliases, their signatures and their verification sync across devices: what you verify on one device applies on all of them. On iPhone, verified aliases are offered in the From field too.

Reply snippets

Canned texts you drop into a message. Create them in the desktop app under Settings → Mail preferences → Reply snippets (Add snippet: Name, Shortcut, Text).

• Inserting: in the compose window type ;shortcut and a space, or pick a snippet in the command palette (⌘ K). After the space, the shortcut turns into the snippet’s text.
• A shortcut may contain letters, digits, “-” and “_” (24 characters at most), and each snippet needs a different one.
• Variables: {jmeno} is the recipient’s first name, {datum} today’s date and {podpis} your signature.
• Limits: at most 100 snippets, one snippet’s text at most 10,000 characters, and all together at most 256 KB. If you go over, Letos says so and offers to shorten the text or delete a snippet.
• Snippets sync across your devices.

OpenPGP

Letos can sign and encrypt messages with OpenPGP, and for a received message verify the signature or open it with your key. You manage the keys yourself.

• Keys: Settings → Security → OpenPGP keys (on iPhone in Settings under Security). You can Paste a key (public, or your private one) and Save key, Create a new key, or Find a key by address. The lookup goes to the web site of that address’s domain (Web Key Directory) and only runs when you click.
• Keys stay in this device’s key storage and are never synced. Deleting a private key is permanent: messages encrypted to that key can no longer be opened.
• When writing (desktop app), the compose window has Sign and Encrypt switches. Signing needs your private key for the sending address. When a recipient’s key is missing, Letos says so (No key for: …) and offers Find key; you can also paste a key manually in Settings → Security.
• Limits: a signed or encrypted message can’t have attachments yet, and an encrypted message can’t be sent with Bcc recipients. Letos tells you up front.
• On a received message (desktop app) you see a label: Signature is valid, Encrypted, signature is valid, Encrypted, opened with your key, Signature is invalid, the message changed after signing, or Signature cannot be verified, the sender’s key is missing.
• Watch the address: when the key belongs to a different address than the one the message came from, Letos says The key belongs to a different address than the one this message came from. In a signed message only the text marked as signed is signed. Anything else in the message is not.
• In the web version OpenPGP isn’t available and the switches aren’t shown.

Attachments

Attachments appear below the message as chips with an icon for the type (image, text, document, archive, other). In the message list, a paperclip shows that a message has an attachment.

• Images and text files open in a preview right inside Letos.
• Other files (PDF, Word, Excel…) are downloaded on the computer to a temporary folder and opened in the system’s default app (e.g. Preview). On the iPhone they open in the system preview. In the web version the file is downloaded.
• For your safety, Letos doesn’t open executable files — it only shows them in Finder.
• More options: Save to Downloads, right-click Save as…, Download all and, for an .ics invitation, Add to calendar.

When writing, add an attachment with Attach file or by dragging it in.

Attachment summary

For an attachment in a message you can ask for Summarize attachment. The button appears for PDF, DOCX, TXT and MD attachments, and only when AI is ready. The text is extracted on your device. Only the text, not the file, is sent to the model, and only after your consent — the same as for other AI (AI).

• When the file name looks like it concerns finances or health, Letos asks once more (Summarize anyway).
• For a long attachment the summary covers only its beginning, and Letos says so.
• When no text can be read from the attachment — for example scanned images, or an encrypted or damaged PDF — Letos says why. When the summary fails, it offers Try again.
• You can copy the finished summary with Copy, or turn it into a task with Create task.

Sender rules

In Settings → Rules (or by right-clicking a message) you set what should happen to mail automatically.

Action	What it does
Archive	The mail is hidden from the inbox.
Delete	The mail goes to the trash (it can be restored).
To spam	The mail goes to spam.
Create task	Every new e-mail becomes a task in the Inbox.

A rule applies to a sender (an address), a whole domain (e.g. example.com) or — only for Create task — a subject that contains the given words. A specific sender beats a domain. Rules also apply to mail already in your inbox; Create task only applies to newly arriving mail.

Newsletters

• The Cleanup assistant shows senders you’d probably want to unsubscribe from.
• A message with an unsubscribe link has Unsubscribe.
• With AI turned on you can sort a thread into Action / FYI / Newsletter.
• A sender rule can archive a newsletter straight away.

Awaiting reply

The Awaiting reply button shows e-mails you sent that nobody has answered yet. With AI, Letos can Draft a follow-up.

Search

The / key opens search across mail, tasks and calendar. Mail is searched first in what’s downloaded on the device, and in the On the server section also directly at your provider. Letos gradually fetches older mail history in the background (Inbox, Sent, Archive; Spam and Trash only if you turn them on).

Operators

Besides words, you can use operators when searching mail. Separate them with spaces and combine them freely.

Operator	What it does
from:address	Messages from a sender (part of the name or address; put a name with a space in quotes: from:"Jan Novák").
to:address	Messages sent to a recipient.
has:attachment	Only messages with an attachment (has:příloha works too).
is:unread / is:read	Only unread / read (is:nepřečtené / is:přečtené work too).
in:inbox / in:archive / in:spam	Only in that folder.
after:date	Messages from that day and newer.
before:date	Messages older than the date.
"exact phrase"	Finds all the words right next to each other.
-word or -"phrase"	Excludes messages containing the word or phrase.

Write the date as 2026-10-16 or 16.10.2026, or as a word: today, yesterday, tomorrow (the Czech dnes, včera, předevčírem, zítra work too). Anything Letos doesn’t recognize (such as subject:) is searched as plain text.

Spell check

Settings → Mail preferences → Spell check: Off, Spelling or Spelling + grammar (AI).

• Languages: Czech and English, or automatic detection.
• Dictionaries are downloaded on first use and stay on the device.
• You can Add to dictionary or Ignore a word.
• The Check grammar button checks grammar and needs local AI.

Spell check is in the desktop app; it’s not on the iPhone yet.

AI drafts

With AI turned on, the compose window has Write with AI: type your intent (e.g. “agree, suggest Tuesday”), pick a tone (Neutral, Formal, Friendly) and click Create draft. You always read and edit the draft yourself — nothing is sent without you. How to turn AI on is in AI.

iPhone gestures

• Swipe right toggles read / unread.
• Swipe left shows Snooze (tomorrow morning) and Archive.
• Long press opens a menu with more actions, including delete.
• Tapping the Mail tab again takes you back to the main mail page.