Mailboxes
Connect sender accounts, providers, and how they are assigned to workers.
A mailbox is a sender account you connect to Warmbly. Every warmup message and campaign email goes out through one you own.
Connecting an account
Open Accounts and choose Add account.
| Provider | Method | Notes |
|---|---|---|
| Gmail / Google Workspace | OAuth (gmail) | Recommended. No password stored. Sends and syncs over the Gmail API |
| Outlook / Microsoft 365 | OAuth (outlook) | Recommended. No password stored. Runs on Microsoft Graph |
| Any other server | IMAP + SMTP (smtp_imap) | Custom domains, self-hosted, or providers without OAuth |
OAuth sends you to your provider's consent screen and returns a token instead of a password. Both OAuth providers use the provider's native API, never IMAP or SMTP, so consent asks to send mail and to read and organize your mailbox. It survives password changes and needs no app passwords or server settings.
IMAP / SMTP needs host, port, username, and password for each direction:
SMTP host: smtp.yourprovider.com port: 465 username: [email protected]
IMAP host: imap.yourprovider.com port: 993 username: [email protected]With two-factor authentication on, generate an app password in your provider's security settings and use that.
Authentication runs on connect
Credentials and both connections are validated when you add the account, so wrong settings fail immediately rather than silently at send time. Tokens and credentials are sealed with envelope encryption before they touch storage.
Limits: 200 mailboxes per workspace by default (higher allowances come through a reviewed limit-increase request), and 5 new mailboxes per workspace per day as an abuse guardrail that resets daily. Spread large onboarding batches across days.
What gets synced
Connecting a mailbox does two things: it imports the mailbox's recent history, and from then on it follows new mail as it arrives. Both are the same on every provider.
The import brings in the last 90 days, newest first, up to 5,000 messages per mailbox (the defaults; a self-hosted instance can change both under Instance settings). It reads the inbox, sent mail and archive (plus your own folders on Gmail and IMAP), and skips trash, drafts, spam and Gmail's "All Mail". You can watch it in the mailbox drawer's Sync card: a progress bar with a running count while it works, then "Up to date" with what was imported. Because it runs newest first, the mail you would look for is there within the first minute; a large mailbox finishes over the next while at a steady pace.
Live sync then follows every folder the provider exposes, including junk (so placement problems are visible) and sent mail (so a conversation shows both sides). Read state, flags, deletions and moves are mirrored too.
Fair use, not a hard cap
There is a budget on how much new mail one mailbox stores per day (2,000 by default) and how much a whole workspace stores per day (25,000), plus a short burst limit so a mailing-list storm cannot swamp the workers. Mail over a budget is not dropped: it waits on the server with the sync cursor held, and comes in when the window rolls. Replies to your own outreach have their own budget and are never held behind ordinary inbound mail. The drawer says "Waiting on the sync budget until ..." while this is happening, and the mailbox checks back less often until then.
Only two patterns deactivate a mailbox's sync, and both mean something is wrong upstream: a flood (thousands of new messages in a single hour, more than any real inbox produces) or exceeding the daily budget on three of the last seven days. The mailbox then shows the reason under Needs attention; fix what is delivering that volume into it, or ask your administrator to raise the budget, and reactivate it.
Sending controls
Set these on the mailbox's Settings tab. They apply to the next scheduled send, not retroactively.
| Control | Default | Range |
|---|---|---|
| Daily campaign cap | 50/day | 0 to 100 |
| Minimum gap between sends | 600s (10 minutes) | A hard floor, with jitter added on top |
The default of 50 is deliberately conservative. 30 to 50/day is the normal safe band; a fresh mailbox should start at 10 to 20 and ramp. Raise the cap only for a mailbox with proven reputation and low complaint and bounce rates.
Do not jump a new mailbox to a high cap
A new mailbox has no reputation. Sudden high volume from a cold inbox is one of the fastest ways to land in spam.
The same tab sets the display name, reply-to (empty uses the mailbox address), signature in plain text and HTML, tags for grouping, and a custom tracking domain. The tracking domain routes opens and clicks through your own subdomain instead of the shared host; Warmbly gives you a CNAME to add and verifies it on save.
Warmup
New mailboxes should warm up before carrying campaign volume. Defaults are 10/day starting volume, +1/day ramp, and a 40/day ceiling.
Start, pause, resume, or stop from the mailbox's Warmup tab, or for several mailboxes at once from the Accounts selection bar. Pausing keeps your ramp progress; stopping resets it, so a restart begins at the base volume again.
Keep warmup running after campaigns begin rather than switching it off once a mailbox looks ready. See Warmup.
Warmup is a paid feature
The model still supports separate free and premium pools, but access is gated to paid workspaces today.
Worker assignment
You never pick a worker. Warmbly assigns each mailbox to a sending worker automatically and can move it later. Workers are the machines that send and sync, so spreading mailboxes across them spreads sending across network identities and IPs.
| Workspace | Placement |
|---|---|
| Free / trial | Shared free-tier workers |
| Paid | Shared premium workers |
| Plans including dedicated workers | A dedicated worker bound to the workspace, allocated on demand, falling back to shared premium and retrying later |
Within a tier, Warmbly picks the least-loaded healthy worker with capacity rather than packing onto the first one. Each mailbox contributes a load weight, so a worker's planned volume tracks the sum of its mailboxes' budgets.
Risk is segregated. A degraded, risky, or quarantined mailbox is never placed on a clean worker beside trusted inboxes, so one struggling mailbox cannot drag down the reputation others depend on.
Mailboxes migrate automatically when a trial upgrades, a subscription ends, a workspace moves to or from a dedicated worker, or a risk band changes. No action needed.
Health
The Accounts list groups mailboxes as Healthy (sending normally), Warming (ramping through warmup), or Needs attention (paused, failing, or not sending), each row showing a live state and score. A drop between refreshes notifies you rather than waiting to be noticed.
The detail drawer runs a live SPF, DKIM, and DMARC check on your sending domain. Confirm it is green before sending; major providers require alignment for bulk and cold mail.
Underneath, health moves through healthy, watch, throttled, quarantined, and blocked. These feed warmup pool selection, which only picks healthy mailboxes as partners, so an unhealthy one can be lowered in volume, removed from the pool, or blocked entirely. A blocked mailbox shows the reason and any appeal option on the Warmup tab, and must requalify on a fresh probation sample rather than waiting out the clock.
Health protects the pool
These controls act earlier than the point where providers start penalizing senders. Low complaint rate and low spam placement matter more than maximum throughput.