Webmail

Webmail lets people read and send mail in a browser, with nothing to install. It works for accounts on your own domains and on shared domains such as free addresses.

It lives at https://<your-host>/mail, or at the root of its own host name (for example https://webmail.mailo.city) when the operator sets one. The Sign in button on the homepage always gets you there.

Signing in

Use your full email address and the password your administrator gave you (or chose at signup). Aliases and +tag addresses do not sign in; use the primary address.

Webmail is a plan feature (webmail). If your plan does not include it, signing in says so; mail apps over IMAP and SMTP may still work.

You stay signed in for up to 7 days, or until 24 hours pass without using it. Sign out from the button at the top right. Changing your password signs you out of webmail on every device, and so does an administrator suspending your account.

After 10 wrong passwords for one address within 15 minutes, sign-in is paused for that address. Wait and try again; the same pause covers mail apps.

Reading

The left column lists your folders with the number of unread messages (for Drafts, the number of drafts). On a phone, open it with the folder button at the top left.
The middle column lists the messages in the folder, newest first, 50 at a time; Load more shows older ones. Each sender has a round picture: their brand logo when it is verified (see Brand logos), otherwise their initials.
Search looks through the current folder: subjects, senders, recipients, the whole text of each message and attachment names. See Searching mail.
New mail appears within a few seconds without reloading the page, and the tab title shows the inbox's unread count. Desktop notifications are optional. See New mail without reloading.

Opening a message marks it read. Mark unread puts it back. Star flags it; mail apps show the same flag.

Source and headers

Source and headers (the </> button above a message) shows the message as it arrived:

Headers: every header field, including the Received lines that trace its path between servers, Authentication-Results with its SPF, DKIM and DMARC results, and any spam scores. This is what a support desk usually asks for.
Full source: the whole raw message, headers and body, as plain text. Very large messages show their first 2 MB; download them for the rest.

Copy puts what is shown on the clipboard, and Download .eml saves the message as a file any mail app can open. Nothing in the source is run or loaded: it is shown as text. Back to message returns to the normal view.

Cc and Bcc

When writing, Cc / Bcc under the To field shows both fields. Bcc recipients get the message but nobody sees them: the Bcc line is taken out of every delivered copy and kept only in your Sent copy, where Bcc shows above the message.

HTML messages and remote images

Messages written in HTML are shown as their sender designed them, in a locked-down frame: scripts, forms and plugins never run, and links open in a new tab.

Images stored on other servers are not loaded. Senders often use them to learn when and where you opened a message, so webmail blocks them and says so above the message. Images sent inside the message (attached or inline) are not affected by this.

Press Load images to see them for that message. Webmail then fetches them through the server: the sender can tell the message was opened, but sees the server's address instead of yours, and never your browser or cookies. Only ordinary pictures (PNG, JPEG, GIF, WebP, AVIF, BMP, ICO) up to 10 MB are shown. Pictures used as backgrounds or in style sheets stay blocked. The choice is not remembered; the next message starts blocked again.

Writing and sending

Compose opens a new message. Reply, Reply all and Forward fill in the recipients, subject and quoted text; forwarding keeps the attachments.
Separate addresses with commas. You can write Name <name@example.com> or just the address.
From lists your address and your aliases. Replies start from the address the message was sent to when it is one of yours.
Attach adds files. Each message, attachments included, must fit your plan's message size limit.
Save draft keeps the message in Drafts. Open it from Drafts to carry on. Discard deletes the draft. While you write, the draft is also saved by itself every 15 seconds when something changed ("Saved 10:31").
Send waits 5 seconds with an Undo button, then puts the message in Sent and delivers it. Choose 0, 5, 10, 20 or 30 seconds under Settings → Writing (this browser only). The message is in Drafts while it waits.
Send later picks a time (later today, tomorrow morning, Monday morning, next week, or any date and time in the next year). The message waits in Drafts with a scheduled badge and is sent at that time, then moves to Sent. Open it from Drafts to see when, or Cancel sending to keep it as an ordinary draft you can edit again. Scheduled messages are sent by the server, so your browser can be closed.
Send puts the message in Sent and delivers it. If it cannot be sent (an unknown address on your own domain, a sending limit, a plan limit), you see why and the message stays in Drafts.

Blind copies (Bcc) are delivered without the Bcc line, so other recipients never see them. Your copy in Sent keeps it.

Mail sent from webmail goes through the same checks and limits as mail apps on ports 465 and 587: it can only come from your own addresses, it counts against your plan's sending limits, and mail to other domains is signed with your domain's DKIM key and queued (see Sending mail). Mail-app sending (smtp_submission) does not need to be in your plan for webmail to send.

Organising

Archive moves a message to Archive, Junk to Junk, and Not junk back to the inbox.
Delete moves a message to Trash. Deleting from Trash removes it for good, and Empty in Trash removes everything there.
Move to… moves a message to any other folder. New folder in the left column adds one.
Several at once: tick the box at the start of each row (Shift-click ticks a range; the box at the top ticks every row shown). A bar then offers mark read or unread, star, archive, junk or not junk, delete and move, for all of them (whole conversations when they are grouped).
Drag and drop: drag a message, or the ticked ones, onto a folder on the left.
Your own folders can be renamed or deleted with the pencil and bin next to the folder's name above the list. Deleting a folder moves its messages to Trash first.
Block sender (on an open message) adds a filter that deletes their mail from now on, and moves the conversation to Trash. Undo it under Filters, where it is the rule "Blocked: …".
Unsubscribe from this list appears under the sender of mailing-list mail that offers it. The server unsubscribes you with one click when the list supports that (so the list never sees your browser), or opens an email or the list's page to do it. Use it only for mail you signed up for; for spam, use Junk or Block sender.
Report spam and Report phishing move a message to Junk and send a copy to your administrators (see Spam filtering).
Snooze (on an open message, or on ticked ones) hides mail until a time you pick. It moves to a Snoozed folder and comes back, unread, to the folder it came from at that time. Open it in Snoozed and choose Bring back now to wake it early.
Mute (on an open conversation) files new replies to it in Archive, already read, so a long thread stops filling your inbox. Unmute turns it back on. Muting applies to mail as it arrives, through either MX server.
Print prints just the open message.
Open next to an image or PDF attachment shows it in a new tab; other files download.
The bar at the bottom of the folder list shows how much of your storage you use.

Installing webmail as an app

Webmail can be installed like an app: in Chrome or Edge choose Install in the address bar (or the menu), on iPhone and iPad Share → Add to Home Screen, and on Android Add to Home screen. It opens in its own window with its own icon. The app keeps only webmail's own pages and scripts so it starts quickly; your mail is never stored on the device, so it still needs a connection.

Templates

In a message, Templates… → Save this message as a template keeps what you wrote (without your signature) in a Templates folder, named after the subject. Pick it from Templates… in any new message to insert it. Because templates are messages in a folder, they are the same in every browser and in mail apps; delete one there to remove it.

Team templates

A team can also keep templates for everyone on it: they are listed under Team in Templates…, the most used first. Picking one inserts it and gives a new message its subject.

Team admins, and members whose team role has Templates, add and change them in the team manager (Templates), or share the message they are writing with Templates… → Share this message with the team.

A team template is inserted with plain formatting only: bold, italics, lists, links and quotes are kept, and anything else (images, scripts, styles) is dropped. So nobody can slip something into a teammate's message through a template.

Keyboard shortcuts

Press ? to see them. They work whenever you are not typing in a field: j and k move through messages (in the list, a cursor), Enter opens, e archives, # deletes, v moves to a folder, z undoes the last move, c writes, Ctrl+Enter or ⌘+Enter sends, and g then i, t, d or a goes to a folder. Turn single-key shortcuts off under Settings → Keyboard shortcuts. Every key, also for the calendar and contacts, is in Keyboard shortcuts.

Light and dark

The half-circle button switches between light and dark. Webmail starts in your device's setting and remembers your choice in that browser.

For administrators and developers

Webmail is a client of the JMAP API at /jmap. It signs in through /api/mail/session (see api/webmail.yaml) and then sends the session cookie with a CSRF token instead of a password. Anything it does, a JMAP client can do with Basic authentication.
Writing formats and signatures are described in Writing mail. Names and signatures are JMAP Identity/set updates, stored per address.
Sending uses JMAP Identity/get, Email/set (create) and EmailSubmission/set, with onSuccessUpdateEmail to move the message from Drafts to Sent. A submission with sendAt (a time in the next year), or the SMTP HOLDUNTIL / HOLDFOR parameters in envelope.mailFrom.parameters (RFC 4865, advertised as maxDelayedSend), is kept with undoStatus: "pending" and sent at that time, when its onSuccessUpdateEmail patch is applied. EmailSubmission/get and /query list pending ones; set undoStatus to "canceled" (or destroy it) to cancel. Others are sent at once and not kept.
Snooze and mute are under /api/mail/later, /api/mail/snooze and /api/mail/mute (see api/webmail.yaml).
Email/set create takes from, to, cc, bcc, replyTo, subject, sentAt, inReplyTo, references, one text/plain and/or one text/html body from bodyValues, and attachments by blobId (uploaded blobs, or parts of stored messages). Other properties are refused; build anything richer yourself and use Email/import.
Email/query filters by inMailbox and text.
Its own host name. In the admin panel under Settings → Host names (or PATCH /v1/settings with webmailHost), set a name such as webmail.mailo.city. Before saving, point that name's DNS (A and AAAA, or a CNAME) at this server. Webmail is then served at the root of that host, and /mail on any other host (including the homepage's Sign in button) redirects there. With automatic certificates, one is issued for the name at its first visit; with a fixed certificate (CORPSUITE_TLS_CERT), the name must already be on it. JMAP and the sign-in API answer on every host, so mail apps are unaffected. The name must differ from the server's own host name, which keeps the homepage. Clear the field to put webmail back at /mail. A change takes effect at once on the server that saved it, and within 30 seconds on others.
Webmail on your customers' own host names (for example mail.customer.com) comes with the custom-domain certificates in M1.

Not there yet

See Contacts for address books and completion. Reading mail without a connection is not offered: the installed app keeps no mail on the device.