Warmerly
Size not published.
Warmerly
Warmbox
One-to-one · Warmup network
Warmup network
One row, in depth: what each tool does, the verified numbers, and who each suits.
Warmbox details read from its pricing, home, features, agency and checker pages and its help centre on 21 October 2026.
Warmerly
Size not published.
Warmbox
More than 35,000 private inboxes from more than 100 countries, aged 2 weeks to 15 years, as it states.
The short answer
Warmup network, in one look.
Warmerly does not publish a network size. Warmup mail goes between real mailboxes in one pool, including other customers' mailboxes, and each mailbox's daily quota is capped by provider. Warmbox says its private network has more than 35,000 inboxes from more than 100 countries, aged from 2 weeks to 15 years. Last checked 22 October 2026.
WarmboxWarmbox ahead on this row
More than 35,000 private inboxes from more than 100 countries, aged 2 weeks to 15 years, as it states.
The picture
Drawn side by side.
The network, as each page states it
Each cloud is for one statement. Not a scale for Warmerly's network
WarmerlyWarmbox
A stated number is a claim about size, not a result. Read on warmbox.ai, 21 October 2026.
How each describes its pool
What the pages say
WarmerlyWarmbox
Real mailboxes in one pool
- Includes other customers' mailboxes
- No repeat contact within 72 hours
- Gmail 40, Outlook 30, Zoho 25 a day
A private network
- Constantly checked and improved
- Mix of the main providers
- In every plan
Neither company publishes placement results from its network.
How Warmerly does it
Warmerly, in detail.
Real mailboxes in one pool, with no published size.
01
No published size
We do not publish a network size, so none is drawn here.
Warmerly product, checked 21 October 2026
02
Threaded warmup emails
Warmup mail goes between real mailboxes in one pool, including other customers' mailboxes. The recipient opens, replies and quotes the earlier message, up to a set thread depth.
Warmerly product, checked 21 October 2026
03
Repeat contact is limited
A sender does not write to the same recipient twice within 72 hours, relaxing to 48 and then 24 if the pool runs short.
Warmerly product, checked 21 October 2026
04
A cap on what each mailbox sends
A mailbox's warmup quota is held to 40 a day on Gmail, 30 on Outlook and 25 on Zoho, however large the pool is.
Warmerly product, checked 21 October 2026
05
Who your partners are
Partners are other customers' mailboxes enrolled in warmup and mailboxes Warmerly runs itself. Other mailboxes you own can be partners too, and the Warmup Network Participation Terms say what other participants can see.
Warmerly product, checked 21 October 2026
06
How a partner is picked
Eligible candidates are weighted by how busy each is today, by how many emails this sender has already sent to that provider today, and by the candidate's own sending volume. That spreads load across the pool and across providers.
Warmerly product, checked 21 October 2026
07
A pool ceiling that is published
A sender doing N emails a day needs roughly 3N distinct partners in a 72-hour window, so a pool of P mailboxes supports about (P - 1) / 3 emails per sender per day. The no-repeat window relaxes to 48 and then 24 hours if the pool runs short.
Warmerly product, checked 21 October 2026
08
Dead ends are skipped
A recipient whose mail is accepted but never found, below 20% of at least 20 resolved jobs in seven days, is dropped as a recipient until the evidence ages out. It can still send.
Warmerly product, checked 21 October 2026
09
Low-reputation addresses are avoided
Hosted senders do not write to a named list of low-reputation domains and top-level domains, and do not reply to them either.
Warmerly product, checked 21 October 2026
10
Our own domain stays out
Mailboxes on Warmerly's own brand domain are kept out of the pool, so warmup never looks like mail from the brand domain.
Warmerly product, checked 21 October 2026
11
Free mailboxes pair separately
Free sandbox mailboxes pair with hosted mailboxes only, so a throwaway signup does not send warmup mail from our addresses to customers' or strangers' mailboxes.
Warmerly product, checked 21 October 2026
12
Content from a checked corpus
Each message is assembled from subjects, openings, bodies and closings in four categories weighted 40, 20, 20 and 20 across follow-up, introduction, scheduling and check-in, with no links, no currency or percentages and no fake reply subjects.
Warmerly product, checked 21 October 2026
How Warmbox does it
Warmbox, in detail.
A large private network, described by size, reach and age.
01
35,000 private inboxes
The home page and features page both state a network of more than 35,000 private inboxes, "constantly checked & improved".
warmbox.ai/the-best-email-warm-up-solution-discover-our-features · read 21 October 2026
02
More than 100 countries
The features page says the inboxes come from more than 100 countries and are aged from 2 weeks to 15 years.
warmbox.ai/the-best-email-warm-up-solution-discover-our-features · read 21 October 2026
03
A mix of providers
The home page says the network is a mix of the most important email service providers. No split by provider is given.
warmbox.ai · read 21 October 2026
04
The network is in every plan
"Private inboxes network" is on the list of features included in all plans.
warmbox.ai/pricing · read 21 October 2026
05
Aged inboxes, from the help centre
Its help article says the inboxes range from 1 month to 15 years old and calls interaction with aged accounts a trust signal for providers.
help.warmbox.ai/en/articles/4803429-the-warmbox-inbox-network · read 22 October 2026
06
Curated, not random accounts
The help article says the network is private and managed by its tech team, and that the accounts are curated to look like real, established users.
help.warmbox.ai/en/articles/4803429-the-warmbox-inbox-network · read 22 October 2026
07
Monitored daily
The same article says Warmbox monitors its mailboxes daily to keep them at what it calls High Authority status. No test or threshold is given.
help.warmbox.ai/en/articles/4803429-the-warmbox-inbox-network · read 22 October 2026
08
What the network does to your mail
The article says network inboxes open your emails, mark them as favourite and reply, and that your emails are rescued from spam at all major providers and a range of private domains.
help.warmbox.ai/en/articles/4803429-the-warmbox-inbox-network · read 22 October 2026
09
Millions of templates
The features page says millions of realistic email templates are used to create natural conversations between your inbox and the network.
warmbox.ai/the-best-email-warm-up-solution-discover-our-features · read 22 October 2026
10
Human-like text
The features and pricing pages list "Humans realistic (GPT4 & Hybrid)" among the features in all plans, which we read as AI-written text mixed with templates. The pages do not explain the mix.
warmbox.ai/pricing · read 22 October 2026
11
A trust figure
The home and features pages say Warmbox is trusted by more than 5,000 companies. No customer names or method are given.
warmbox.ai · read 22 October 2026
12
Why the network matters, in its words
The home page says 51% of emails sent land in spam and presents the network as the way to avoid that. No source for the 51% is given.
warmbox.ai · read 22 October 2026
What Warmbox does not say
We looked, and found no statement on these. That is about its published pages only, not about the product.
- How the network inboxes are sourced or checked
- The split by provider
- Any figure for how often one inbox is used
- Whether other customers' inboxes are part of the network
- How often each network inbox is used
- Whether network inboxes are checked for blocklists or what happens when one fails
- Any rule that stops one pair writing to each other repeatedly
Where the sources disagree
We report each version rather than pick one.
- Warmbox states the network as more than 35,000 inboxes on its home, features and pricing pages, and as more than 30,000 in its help articles "What is Warmbox?" and "The Warmbox inbox network". We show both.
- Warmbox states inbox age as 2 weeks to 15 years on its features page and 1 month to 15 years in its help article.
The numbers
Only what we could verify.
| Measure | Warmerly | Warmbox |
|---|---|---|
| Warmup network | Size not published. | More than 35,000 private inboxes from more than 100 countries, aged 2 weeks to 15 years, as it states. |
| Private inboxes in the network | Not published | More than 35,000 |
| Countries | Not published | More than 100 |
| Inbox age | Not published | 2 weeks to 15 years |
| Daily cap on one Gmail mailbox | 40 a day | Not stated |
| Inbox age range, help centre | Not published | 1 month to 15 years |
| Network size, help centre | Not published | More than 30,000 |
| Repeat contact limit | No repeat to one recipient within 72 hours, relaxing to 48 then 24 | Not stated |
| Daily cap on one Outlook mailbox | 30 a day | Not stated |
| Daily cap on one Zoho mailbox | 25 a day | Not stated |
| Thread depth in warmup | Up to 3 | Not stated |
| Share of the network in every plan | Same pool on every plan | Network listed in all plans |
| Companies it says use it | Not published | More than 5,000 |
In practice
What it means for you.
Our reading of the facts above. Not a promise, and not the only reasonable reading.
A bigger pool is a claim, not a result
Neither company publishes placement results from its network. Size says how many partners there are, not where your mail lands.
Ask about who is in the pool
Warmerly's pool includes other customers' mailboxes. Warmbox calls its network private. Its pages do not say how inboxes are sourced.
Ask what the pool is made of
A network can be made of the vendor's own accounts, other customers or both. Warmerly says its pool is other customers' mailboxes plus mailboxes it runs itself. Warmbox calls its network private and curated, and does not say how the accounts are obtained.
Size matters less than spread
A pool that is large but sends your mail to the same few partners every day would look odd to a provider. Warmerly publishes its repeat-contact rule. Warmbox publishes no such rule, so ask its team before you rely on size alone.
Read the numbers it gives
Warmbox gives two different network sizes on its own pages: more than 35,000 on the marketing pages and more than 30,000 in the help centre. Both are its own figures. The difference is small next to the question of how your mail is actually treated.
A reasonable test for either tool
Connect one mailbox, leave the settings alone for a few weeks and watch whether spam placement of warm-up mail falls. That tells you more than a headline size, and it costs one inbox.
Keep your own sending steady
No network can cover a sudden jump in real volume. Warmbox's own guidance on volume says scaling gradually avoids unusual activity alerts, and Warmerly's ramp is built on the same idea.
Who it suits
Pick the one that fits.
Warmerly
Warmerly is the better fit if
- You want repeat-contact limits and provider caps written down
- You are happy with a smaller pool that is not sized publicly
- You want to know the rules that decide who writes to whom, in writing
- You want the pool described in a way you can check against published code and documents
- You prefer warmup that never writes to a listed set of low-reputation domains
- You want one network on every plan with no extra price for it
- You want Free mailboxes kept away from other customers' addresses
Warmbox
Warmbox is the better fit if
- You want a stated network of 35,000 or more inboxes
- You want a network that is described by country and inbox age
- You want a network described by size, countries and age, even if the figures are its own claims
- You like the idea of a curated private network of aged inboxes
- You want the vendor to say its network is monitored daily
- You want a larger stated network than Warmerly gives, and are willing to accept that the claim is unverified
- You want a human-sounding mix of templates and AI text listed as a feature
Questions
How big is Warmbox's network?
More than 35,000 inboxes from more than 100 countries, aged 2 weeks to 15 years. Its help centre says more than 30,000, so the figures differ.
Does Warmerly publish its network size?
No. Warmup mail goes between real mailboxes in one pool, including other customers' mailboxes.
What limits does Warmerly set per mailbox?
40 a day on Gmail, 30 on Outlook and 25 on Zoho, with thread depth up to 3.
How often does Warmerly repeat a contact?
Not to one recipient within 72 hours, relaxing to 48 then 24.
Sources
- Warmbox features
- Warmbox home
- Warmbox pricing
- Warmbox help: the inbox network
- Warmbox help: what is Warmbox
Warmbox pages were read on 21 October 2026. Plans and wording change, so check the vendor's own page before you decide. Warmerly details come from the product as it runs today.
More features
See it on your own mailbox.
Connect a mailbox. Warmerly runs alongside whatever you send from now, so you can compare before you move anything.
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