Inbox rotation
Spread the load. Protect every mailbox.
Every campaign is shared across its mailboxes, each sending on its own irregular rhythm and inside its own limits. When a provider pushes back, Mailnitrix reads the signal and responds the right way.
Sending timeline · last hour
Example
alex@yourco.com
8 sentsam@yourco.com
7 sentpriya@tryyourco.com
7 sentjordan@tryyourco.com
421 throttled · cooling 1hEach mailbox keeps its own irregular rhythm. When one gets throttled, its queued emails move to the others.
Rotation
Many mailboxes, one campaign.
Choose the mailboxes for a campaign and Mailnitrix divides the recipients between them based on how much room each one has left today. Each mailbox also cycles through your templates, so the same wording never goes out in a burst.
- Mix Gmail, Workspace, Outlook and Microsoft 365 in one campaign
- Unlimited mailboxes on paid plans
- Pending emails move to healthy mailboxes when one needs a rest
- See live stats for every mailbox while the campaign runs
Q4 founder outreach
1,284 / 4,000 sent · 4 mailboxes
- alex@yourco.comWorkspace27/40 todaynext in 0:18
- sam@yourco.comWorkspace25/40 todaynext in 0:52
- priya@tryyourco.comOutlook22/35 todaynext in 1:27
- jordan@tryyourco.comGmail31/40 todayCooling down · 47m
Live activity
- ↗ sam → ruth@adventure-works.comB · 09:40:58
- ↗ alex → kai@wingtiptoys.comA · 09:40:09
- ↗ priya → omar@tailspintoys.comC · 09:39:31
Pacing
Human rhythm, not machine-gun bursts.
Every mailbox sends on its own randomised schedule, using the gap you choose per campaign. Two emails from the same mailbox never leave at the same moment, even after a restart or a backlog.
- Random gaps between sends, 20 seconds to 2 minutes by default
- Limits counted over a rolling 24 hours, not a midnight reset
- Backlogs are re-spaced, never fired all at once
- Scheduled campaigns start on time, on their own
Gaps between sends · one mailbox
Error-aware cooldowns
Every provider error gets the right response.
Most tools treat every failure the same way. Mailnitrix reads the status code and wording Gmail and Microsoft send back, then decides who is affected and for how long.
| What the provider says | What Mailnitrix does |
|---|---|
Daily sending limit reached Gmail 550 5.4.5 | The mailbox rests for 24 hours. Its queued emails move to other mailboxes. |
Temporary throttling 421 4.7.0, 4.7.28 unusual rate | A 1-hour pause that doubles on repeats, up to 24 hours. No hammering a mailbox that's already being watched. |
Message blocked as spam 550 5.7.1 unsolicited mail | A 6-hour pause, recorded on the mailbox. The recipient isn't marked as bounced; the email is retried from another mailbox. |
Recipient problem 552 5.2.2 mailbox full, 550 5.1.1 no such user | Only that recipient is affected. Your mailbox keeps sending as normal. |
Greylisting and temporary refusals 450 4.2.0 | Retried later instead of being recorded as a bounce. |
Login rejected 535 5.7.8 | The mailbox is flagged so you can fix the password, and stops sending until you do. |
Microsoft turned off SMTP for the mailbox SmtpClientAuthentication is disabled | Sending switches to the Microsoft Graph API automatically and carries on. |
Self-managing campaigns
Pauses itself. Resumes itself.
Before launch you see how much your mailboxes can send today and whether the list fits. Once it runs, the campaign takes care of the rest.
Capacity check
See each mailbox's remaining room today, whether the whole list fits and what to do if it doesn't.
Automatic pause
When no mailbox can send, the campaign pauses with a reason you can read, instead of failing emails.
Automatic resume
As soon as a mailbox has room again, the campaign picks up where it left off. Manual pauses are never touched.
FAQ
Rotation questions.
How many emails should each mailbox send per day?
For cold email, 30 to 40 a day per mailbox is a common safe range, lower for new mailboxes. You set a daily limit per mailbox and Mailnitrix never goes over it in any 24-hour window.
What delay should I use between emails?
The default is a random gap of 20 seconds to 2 minutes per mailbox, and you can change it per campaign. Wider ranges look more human; narrower ranges finish sooner.
What happens if every mailbox hits its limit?
The campaign pauses itself with a clear reason, and resumes on its own once a mailbox has room again. Campaigns you pause by hand stay paused until you resume them.
Do one-off and warmup emails count toward a mailbox's limit?
Yes. Campaign, one-off and warmup emails all count toward the same rolling 24-hour limit, so the total a mailbox sends always stays within what you set.
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