Warmerly
Real mailboxes in one pool, including other customers'. Size not published.
Warmerly
lemwarm
One-to-one · Warmup network
Warmup network
One row, in depth: what each tool does, the verified numbers, and who each suits.
Lemwarm details read from its pricing page, home page, blog and lemlist's help centre on 21 October 2026.
Warmerly
Real mailboxes in one pool, including other customers'. Size not published.
lemwarm
20,000+ domains in 100+ countries on its home page; its FAQ says 20,000+ real users.
The short answer
Warmup network, in one look.
Warmerly does not publish a network size, while Lemwarm says it warms across 20,000+ healthy domains in 100+ countries, though its FAQ describes 20,000+ real users, so its own pages count it two ways. Both exchange mail between real mailboxes rather than bots. Last checked 21 October 2026.
lemwarm
20,000+ domains in 100+ countries on its home page; its FAQ says 20,000+ real users.
The picture
Drawn side by side.
The network, as each page states it
Statements only, not a measurement
Warmerlylemwarm
Size not published
- Real mailboxes in one pool
- Same recipient not within 72 hours
20,000+ domains
- 100+ countries, per its home page
- FAQ: 20,000+ real users
- Lemlist users and lemwarm subscribers, per its blog
Lemwarm's own pages count its network as domains in one place and users in another.
How Warmerly does it
Warmerly, in detail.
A pool of real mailboxes, with no published size.
01
No published size
We do not publish a network size.
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 thread depth of 3.
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
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
05
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, multiplied together.
Warmerly product, checked 21 October 2026
06
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
07
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
08
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
09
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
10
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
11
Threads, not blasts
A reply is queued with the earlier message quoted, up to a thread depth of 3. A first reply is drawn at the recipient's reply rate, and later replies at 35% of it.
Warmerly product, checked 21 October 2026
12
A tuned reply rate
A mailbox's reply rate starts at 30% and moves between 15% and 40%. It rises by 5 points when health is falling or under 60, and falls by 2 points when health is above 75 and rising.
Warmerly product, checked 21 October 2026
13
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
How Lemwarm does it
Lemwarm, in detail.
A large stated network, counted as domains in one place and users in another.
01
20,000+ healthy domains
The home page says to warm up across 20,000+ healthy domains in 100+ countries. 'Real inboxes, real replies, no bots.'
lemwarm.com · read 21 October 2026
02
20,000+ real users
The FAQ says lemwarm warms up your inbox by exchanging safe, real emails with a network of 20,000+ real users.
lemwarm.com · read 21 October 2026
03
A tailored network on Smart
Smart adds a network tailored to your industry. No size is given.
lemwarm.com/pricing · read 21 October 2026
04
Real-life templates
The help centre says Essential's content email uses real-life templates, replacing older content, and the blog says warm-up emails use real-life templates, not generic filler, with conversations kept threaded.
help.lemlist.com/en/articles/8178526-discovering-lemwarm-plans · read 21 October 2026
05
Mailbox age in the network
The blog says you exchange emails with 20,000+ healthy domains, some with 25+ years of history, and 'No fake inboxes.'
lemwarm.com/blog/how-to-boost-your-email-deliverability · read 21 October 2026
06
Real inboxes, real replies
The home page says the warm-up uses real inboxes, real replies, no bots, and that it connects across 100+ countries.
lemwarm.com · read 21 October 2026
07
Used by teams
The blog says lemwarm is used by 10,000+ teams, which describes use, not who is in the network.
lemwarm.com/blog/how-to-boost-your-email-deliverability · read 21 October 2026
08
No reading of your mail
The home page FAQ says lemwarm uses a secure login, never reads your real emails and never touches your contacts.
lemwarm.com · read 21 October 2026
09
Clusters on Smart
lemlist's help centre says Smart uses a questionnaire to adapt the warm-up content and the cluster you are placed in.
help.lemlist.com/en/articles/8178526-discovering-lemwarm-plans · read 21 October 2026
10
Warm-up mail is labelled
The blog says lemwarm emails are auto-labelled so they stay out of your primary view, and the setup article tells you to add a filter in your provider as well.
lemwarm.com/blog/how-to-boost-your-email-deliverability · read 21 October 2026
11
Pauses when peers misbehave
The pause guide includes codes for a provider unreachable or blocking messages, and for a bounce that did not match a known pattern, which pauses after three occurrences.
help.lemlist.com/en/articles/12918125-why-was-lemwarm-paused-full-guide-to-all-pause-reasons-and-how-to-fix-them · read 21 October 2026
What Lemwarm 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 is checked or how bad peers are removed
- How many of the 20,000+ are active at once
- Who is in the lemwarm network, such as lemlist users or other subscribers
- How the network removes a poor peer
- How many of the domains are active at one time
Where the sources disagree
We report each version rather than pick one.
- Network count: the home page says 20,000+ domains in the warm-up section and the hero, but 20,000+ real users in the FAQ.
The numbers
Only what we could verify.
| Measure | Warmerly | lemwarm |
|---|---|---|
| Warmup network | Real mailboxes in one pool, including other customers'. Size not published. | 20,000+ domains in 100+ countries on its home page; its FAQ says 20,000+ real users. |
| Network size stated | Not published | 20,000+ |
| Countries | Not published | 100+ |
| Same recipient twice | Not within 72 hours | Not stated |
| Same recipient twice | Not within 72 hours, relaxing to 48 and 24 | Not stated |
| Pool ceiling per sender | About (P - 1) / 3 a day | Not stated |
| Thread depth | Up to 3 | Not stated |
| Reply rate range | 15% to 40% | Not stated |
| Messages opened | About 90% | Not stated |
| Teams using it | Not published | 10,000+ per its blog |
| Oldest domains | Not published | 25+ years of history |
In practice
What it means for you.
Our reading of the facts above. Not a promise, and not the only reasonable reading.
A number is not the whole picture
At 5 to 25 mailboxes the pool is rarely the first limit. Provider caps and your own content matter more.
Smaller does not mean fake
Both describe real mailboxes. Neither publishes how a poor peer is removed.
Why the pool ceiling matters
Take a pool of 40 eligible mailboxes as an example. The formula supports about 13 emails per sender per day, (40 - 1) / 3. A pool that size cannot give one sender 50 distinct partners every three days, which is why the no-repeat window relaxes, and why pool size matters more at high volume than at 5 to 25 mailboxes.
What 'real' means on each side
Lemwarm says real inboxes and domains with long histories. Warmerly says partners are customers' mailboxes and ones it runs itself. Neither page lets you audit the pool, so the claim is the vendor's own.
Content you can read
Warmerly's message content is a published corpus with rules enforced by a test: no links, no promotional wording, no fake threads. Lemwarm's pages say real-life templates and, on Smart, content adapted to your industry, without publishing the rules.
Same domain, shared reputation
lemlist's help centre says other users on the same domain can damage its reputation, and that a separate domain for outreach is often safer. That holds on any warm-up network, including Warmerly's.
Who it suits
Pick the one that fits.
Warmerly
Warmerly is the better fit if
- You want the pairing and daily caps published
- You run a handful of mailboxes
- You do not need a stated network size
- You want the pairing rules and the pool maths published
- You want to read the rules the message content must follow
- You do not need a stated network size
lemwarm
Lemwarm is the better fit if
- You want a stated network size and an industry-tailored network on Smart
- You are already inside lemlist
- You want a stated network of 20,000+ domains with long histories
- You want an industry-tailored cluster on Smart
- You want a vendor that states it never reads your mail
Questions
Is Lemwarm's network bigger than Warmerly's?
Lemwarm states 20,000+ domains. Warmerly does not publish a figure, so we cannot give a like-for-like comparison, and we do not claim a larger one.
Does network size decide results?
Not by itself. Reputation lives at Gmail and Microsoft, and what you send matters too.
Are my warmup partners other customers?
Yes, and mailboxes Warmerly runs itself. The Warmup Network Participation Terms say what other participants can see.
Is one network more reliable than the other?
We cannot say. Neither publishes active counts or how poor peers are removed, and results depend on your domain, volume and content as much as on pool size.
Does Warmerly read my emails?
Warmup looks for its own warmup messages in your mailbox, to open, move and reply to them. Campaign mail to your prospects is never moved or flagged by warmup.
Sources
Lemwarm 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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