How Instantly warmup works
Instantly's help centre article, How warm up works and why it's important, is the source for everything in the table above, and it is the page that ranks first for the query. It is 650 words long. The mechanism it describes is a shared pool: your mailbox sends warmup emails to other Instantly accounts, they open, reply and move the mail, and Instantly counts the results into a health score. A new account starts at around 10 warmup emails a day and ramps; Instantly asks you to wait two to three weeks and to keep the health score above 90% on a rolling seven days before you start campaigns.
The settings, and what each one does
- Warmup emails per day. Instantly starts a new account at about 10 and ramps. Higher is not better on a domain with no history; the point of a ramp is that the volume climbs on the curve receivers expect.
- The health score. Instantly's measure of how its own warmup mail is landing. Above 90% for a rolling week is Instantly's threshold for starting campaigns. It measures placement inside the pool, not where your outreach lands with prospects, so treat it as necessary rather than sufficient and run a placement test before the first real send.
- The waiting period. Two to three weeks minimum. That matches every serious warmup guide, including MailStrike's 21-day ramp, and the mailboxes that get burned are the ones whose owners skip it.
- Premium and Private pools. Paid add-ons that narrow who your mailbox exchanges mail with. That they exist tells you the default pool's weakness: it is everyone.
Why the pool is the problem
The objection MailStrike hears most on calls is “Instantly already warms my inboxes”. It does. The question is what that warming looks like to Gmail and Microsoft, and the answer has two parts. First, the pool is anyone: every Instantly signup is in it, including the senders you would not want your domain paired with, and reputation is judged by the company a mailbox keeps. Second, it gets caught now: pool warmup is templated, bot-to-bot engagement on a schedule, and Google and Microsoft have built filters that recognize that pattern. Warmup they can detect can count against the domain instead of for it.
Neither point says Instantly's warmup does nothing. It says its engagement is weaker, and riskier, exactly when you need it most: a new domain, a domain in spam, or a set of thirty mailboxes that all need reputation at once.
Running MailStrike alongside Instantly
Instantly sends your campaigns from a mailbox. MailStrike warms that mailbox. The two connect to the same Google Workspace or Microsoft 365 account independently, over OAuth, and neither sees the other. There is no Instantly integration in MailStrike and none is needed.
- 1
Connect the mailboxes Instantly sends from
One-click OAuth for Google Workspace and Microsoft 365, or SMTP and IMAP with an app password. SPF, DKIM, DMARC and MX are checked on connection. Each mailbox gets its own AI persona.
- 2
Set the daily warming volume, leave Instantly's campaigns running
The plan default is 30 a day per mailbox and the defaults reach full volume in 21 days. Warming mail is exchanged only with the MailStrike network and is labelled and archived on arrival, so the inbox Instantly sends from stays clean.
- 3
Decide what to do with Instantly's warmup toggle
You can run both. If you do, keep the combined warmup volume where a real person's correspondence would sit. Most teams switch Instantly's warmup off once the MailStrike ramp is under way, so there is one warming plan, and use Instantly for what it is for: the sequences.
- 4
Read Flashman, then raise Instantly's daily limits
Flashman's daily summary recommends a send volume per mailbox. Raise the campaign limits in Instantly as the recommendation rises, and run a placement test before a big send.
The limits Instantly's settings do not show you
Google Workspace allows 2,000 messages a day per user and Microsoft 365 throttles at 30 a minute with a tenant-wide external cap, so the hard limits are far away from any sensible campaign. The ceiling you hit first is reputation, which is why the safe daily volume for a warmed mailbox is a fraction of the provider cap, and why the per-provider limits are worth knowing anyway.
Instantly's health score is not a placement test
The score tracks where Instantly's own warmup mail lands among Instantly accounts. Your prospects are not Instantly accounts. The only way to know where a campaign lands is to send it to inboxes whose folders you can read, at every provider, which is what a placement test does. MailStrike's Free Deliverability Test scores the email for spam signals and reports inbox, promotions or spam per provider, and every warming plan includes placement tests to run before a large Instantly send.
The short version
Instantly warms through a shared pool, starting a new account at about 10 a day, and asks you to wait two to three weeks with a health score above 90% before campaigns, per its help centre of July 2026. What it does not document is who is in the pool, how the content is written, or whether spam is rescued. For an easy case that may be enough. For a new domain, a recovery or a large mailbox set, MailStrike warms the same mailboxes with an AI persona each, runs alongside Instantly's sending, and needs nothing integrated.
Questions people ask about Instantly warmup
How does Instantly warmup work?
Instantly enrols your mailbox in a shared pool of other Instantly accounts. Your mailbox sends warmup emails to the pool and the pool opens, replies to and moves them; the volume starts at around 10 a day for a new account and ramps. Instantly's help centre says to run it for two to three weeks minimum before starting campaigns, and to keep the warmup health score above 90% on a rolling seven days.
How long does Instantly take to warm up emails?
Instantly's own guidance is a minimum of two to three weeks before campaigns. It does not publish a day at which a mailbox is ready, so treat the health score, not the calendar, as the signal, and test placement before the first send.
What are the best Instantly warmup settings?
Instantly's documentation sets the shape: start a new account at its default of around 10 warmup emails a day, let the ramp climb, keep the health score above 90% for a rolling week, and do not start campaigns until it has held there for two to three weeks. Beyond that the settings that matter are the ones Instantly does not expose: who is in the pool with you and what the warmup content looks like.
What is the Instantly warmup pool?
The set of other Instantly customers' mailboxes your mailbox exchanges warmup mail with. It is shared: whoever signed up for Instantly is in it, including senders whose reputation you would not choose to be paired with. Instantly sells Premium and Private pool add-ons for a smaller or dedicated pool.
Is Instantly's warmup enough on its own?
For an aged domain with a decent history, often yes. For a new domain, a domain recovering from spam, or a large mailbox set, the pool-style engagement is where it falls short: it is shared with everyone on the platform, and its templated pattern is what Google and Microsoft now detect. MailStrike warms the same mailboxes with an AI persona each and runs alongside Instantly's sending.
Can I run MailStrike and Instantly at the same time?
Yes. Both connect to the same Google Workspace or Microsoft 365 mailbox independently: MailStrike to warm it, Instantly to send from it. There is no integration to set up. If you keep Instantly's warmup on as well, the two warmup volumes add up, so keep the total where a real person's correspondence would sit.