5 questions answered.
How long does warmup take?
Plan on 3–6 weeks for a brand-new mailbox to reach a stable warmed state. We ramp +1 / day from a 10 / day start with a 40 / day ceiling.
Do free and premium pools mix?
Only on proven terms. Paid mailboxes are served from the premium pool first; a thin tier borrows the other tier's mailboxes that have been healthy members for at least three days. Dedicated workers still participate in the premium pool by default.
Is self-hosting free?
Yes, the whole platform is Apache 2.0 and free to run, with unlimited mailboxes. When Warmbly Cloud launches, link your instance and we run warmup for up to 10 mailboxes at no cost, or unlimited for $15 a month.
What gets a mailbox quarantined?
≥ 3 invalid warmup tokens in 24h, spam score above 50, complaint rate over 0.10%, or spam-folder placement over 20% on a sufficient sample.
Can I keep warming after I start cold sending?
Yes, and you should. Warmup should keep running even after campaigns begin.
4 questions answered.
What is the per-mailbox cap?
Default 50 cold emails / day with a 10-minute minimum gap. You can lower it. You can raise it, but anything above 50 / day requires positive reputation signals.
How do you spread sending across IPs?
One worker per machine, each with its own IP. We distribute mailboxes across workers and assign campaign leads round-robin across the chosen sender pool, with each lead keeping the mailbox that sent its first email.
Do you offer dedicated IPs?
Business and Enterprise run your sending on a worker machine allocated to your organisation alone, so your reputation is not shared with other customers. We do not sell or manage IPs as a product, and we do not let you bring your own.
What providers do you support?
Google Workspace / Gmail, Microsoft 365 / Outlook, and any SMTP / IMAP provider. iCloud and Zoho are first-class too.
3 questions answered.
How accurate is reply detection?
Reply detection survives quoted text, signatures, "sent from" footers, and forwarded threads. OOO and unsubscribe replies are classified separately.
Can I unify several mailboxes in one view?
Yes, that is the whole point. Filters, search and assignment span every connected mailbox.
Are open and click trackers reliable?
Honestly: opens are noisy because of Apple Mail Privacy and image proxies. We surface opens but never use them for deliverability decisions.
4 questions answered.
Where is data stored?
AWS regions. us-east-1 by default, eu-west-1 on Grow and Business. Custom residency on Enterprise.
How is mailbox auth stored?
Refresh tokens are envelope-encrypted with per-organization KMS-derived data keys. Decrypted keys are cached briefly in Redis, never persisted to disk.
Do you have SOC 2?
SOC 2 Type II audit is in progress. We can share the bridge letter once the report is issued.
Do you sign DPAs?
Yes. Email [email protected] and we will turn it around within 48 hours.
4 questions answered.
Do you charge per email?
No. Each plan includes a fixed daily send budget. Unused volume does not carry over.
What if I disconnect a mailbox mid-month?
Charges are prorated. Reconnecting in the same period does not double-bill you.
Refund policy?
Full refund within 14 days of a paid purchase if the platform did not work for you.
Startup discount?
50% off Grow for one year for pre-seed and seed companies on YC, Antler, EF, Techstars or similar.