Every mailbox keeps a workday, like the person who owns it.
Each mailbox starts at a slightly different time every day, takes a lunch break, spaces its emails unevenly and stops before evening, all in its own timezone. Volume comes from more mailboxes, never from pushing one harder.
28 to 32
cold emails a day
5 to 9
an hour, at most
90 to 420s
between two emails
The defaults for a newly connected mailbox. Change any of them.
Ranges, not fixed values. A new workday is rolled every morning.
You set ranges once. Each day the mailbox picks its hours, break, target and spacing from them and keeps to that day, so a retry or a busy campaign never re-rolls it. Edits apply from the next local day.
- Working days
- Monday to Friday, for warmup and cold mail alike
- Start of the day
- Somewhere between 09:03 and 09:27
- End of the day
- Somewhere between 17:18 and 17:56
- Lunch break
- Starts between 12:00 and 13:30, lasts 30 to 60 minutes
Three clocks. An email goes out only when every clock agrees.
The campaign has its sending window, the mailbox has its workday, and with send-time optimization on, the recipient has their own local hours. Warmbly waits for the moment all of them allow, and never sends outside them to catch up.
- 1The contact’s own timezone field, when it holds a real zone such as America/Denver
- 2The country of their email domain: acme.de reads as Berlin, acme.co.uk as London
- 3The fallback timezone you choose, for everyone else
The path. Your provider delivers your email, not ours.
Warmbly’s workers sign in to your mailbox at Google, Microsoft or your SMTP host and hand the email over. Your provider delivers it from its own servers, so recipients judge your mailbox and your domain, not our infrastructure.
Signed in, not relayed
Google mailboxes send through the Gmail API, Microsoft mailboxes through Microsoft Graph, and every other host over SMTP.
A familiar address
Each mailbox stays on the same worker wherever it can, and moves only when that worker goes down, is throttled or runs far over capacity.
An address of your own
On Business and above, your mailboxes sign in from an address no other customer uses.
Volume. More mailboxes, never one mailbox pushed harder.
Every mailbox has its own cap and its own workday, and a campaign’s day is the sum of them. A second healthy mailbox roughly doubles how fast a campaign works through its leads, while each one stays inside its own limits.
50
cold emails a day per mailbox by default, and the dashboard warns past 100
10 min
between two sends from one mailbox on a fixed schedule
~30
a day on a newly connected mailbox’s rolled plan
5
cold emails a day at most while a mailbox is still warming
Questions. Sending, answered.
Why randomise sending at all?
A mailbox that sends exactly 40 emails at exactly 10-minute intervals from 09:00:00 sharp looks like a machine. Varying the workday, the breaks and the spacing makes it look like the person whose mailbox it is.
Can this make a mailbox send more than its cap?
No. The workday can only lower volume or delay a send. A mailbox capped at 50 that rolls 31 for the day sends at most 31.
Does warmup follow the same workday?
Yes. Warmup keeps the same days, hours and lunch break, so warmup mail never goes out at 3am from a mailbox that keeps office hours. It has its own ramp and doesn’t eat into the cold budget.
Can I send in each recipient’s timezone?
Yes. Send-time optimization holds each email until the recipient’s local clock reaches the hours you choose. It reads the contact’s timezone field first, then the country of their email domain, then a fallback you set.
Do my mailboxes send from your servers?
Your mailboxes send through their own providers, Google, Microsoft or your SMTP host. Warmbly’s workers sign in to those providers for you, and each mailbox is kept on the same worker wherever possible, because a stable sign-in address is what providers trust.
Does the worker’s IP address affect my deliverability?
Recipients never see it. Your provider delivers the email from its own servers, so spam filters judge your mailbox and your domain. The worker’s address only matters to your provider when it signs in, which is why mailboxes are not moved between workers without a reason.
Sending, in more depth
All postsGive your mailboxes a human workday.
Connect a mailbox and it starts with a sensible workday, ready to change whenever you like.