Warmerly
Gmail, Google Workspace, Microsoft 365 and other IMAP and SMTP mailboxes.
Warmerly
Warmbox
One-to-one · Inbox types supported
Inbox types supported
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
Gmail, Google Workspace, Microsoft 365 and other IMAP and SMTP mailboxes.
Warmbox
Gmail, Outlook, Yahoo, iCloud, AOL, Yandex, Zoho, Sendgrid, Sendinblue, Mailgun and Amazon SES, plus any SMTP inbox.
The short answer
Inbox types supported, in one look.
Warmerly connects Gmail and Google Workspace, Microsoft 365 and other IMAP and SMTP mailboxes. Warmbox names Gmail, Outlook, Yahoo, iCloud, AOL, Yandex, Zoho, Sendgrid, Sendinblue, Mailgun and Amazon SES, plus any inbox over SMTP, and has a help article for each. Last checked 22 October 2026.
WarmboxWarmbox ahead on this row
Gmail, Outlook, Yahoo, iCloud, AOL, Yandex, Zoho, Sendgrid, Sendinblue, Mailgun and Amazon SES, plus any SMTP inbox.
The picture
Drawn side by side.
The inboxes each names
As each page lists them
WarmerlyWarmbox
Google and Microsoft, plus IMAP and SMTP
- Gmail
- Google Workspace
- Microsoft 365
- Other IMAP and SMTP mailboxes
11 named, plus any SMTP inbox
- Gmail
- Outlook
- Yahoo
- iCloud
- AOL
- Yandex
- Zoho
- Sendgrid
- Sendinblue
- Mailgun
- Amazon SES
- Any other inbox (SMTP)
Warmbox's list is from its pricing page. Warmerly's is what its mailbox connect flow offers.
Connecting an inbox
The steps each describes
WarmerlyWarmbox
Warmerly
Choose Gmail or Microsoft 365App password or sign-inWarmup starts
Warmbox
Choose one of the named typesGoogle sign-in, app password or SMTPWarm-up starts
Warmbox's Gmail article says sign-in can occasionally pause a campaign after a Google security refresh, and recommends an app password.
How Warmerly does it
Warmerly, in detail.
Gmail, Google Workspace, Microsoft 365 and other IMAP and SMTP mailboxes.
01
Gmail and Google Workspace
Connect with an app password.
Warmerly product, checked 21 October 2026
02
Microsoft 365
Sign in with Microsoft 365.
Warmerly product, checked 21 October 2026
03
Other IMAP and SMTP mailboxes
A mailbox on another provider connects over IMAP and SMTP. Warmup quotas have a cap for Zoho as well as Gmail and Outlook.
Warmerly product, checked 21 October 2026
04
Hosted mailboxes
OneMail mailboxes hosted by Warmerly do not use a plan mailbox slot.
Warmerly product, checked 21 October 2026
05
Five ready settings
The connect form has presets for Gmail and Google Workspace, Outlook and Microsoft 365, Zoho Mail, Namecheap Private Email and a Custom SMTP and IMAP option, each with host and port filled in.
Warmerly product, checked 21 October 2026
06
Gmail uses an app password
Gmail and Google Workspace connect with an app password, which needs 2-Step Verification on first.
Warmerly product, checked 21 October 2026
07
Microsoft by sign-in
Microsoft 365, Outlook.com and Hotmail connect with a one-click Microsoft sign-in. Warmerly uses SMTP and IMAP over that sign-in and does not send through Microsoft Graph.
Warmerly product, checked 21 October 2026
08
Custom SMTP and IMAP
Any other mailbox connects by giving its SMTP and IMAP host, port, user and password. Passwords are encrypted at rest and never returned by the API.
Warmerly product, checked 21 October 2026
09
Provider detection
Given an address, the wizard guesses the provider from the domain's live MX records and fills in the hosts. A domain it cannot place is reported as unsupported with a note.
Warmerly product, checked 21 October 2026
10
Provider daily caps
Warmup volume is held to 40 a day on Gmail, 30 on Outlook, 25 on Zoho and 50 on Namecheap or custom hosts, whatever the ramp would allow.
Warmerly product, checked 21 October 2026
11
No named Yahoo, iCloud, AOL or Yandex preset
Those mailboxes would go through Custom SMTP and IMAP. We have not verified a warmup run on each, so we do not list them as supported.
Warmerly product, checked 21 October 2026
How Warmbox does it
Warmbox, in detail.
Eleven named inbox types and any SMTP inbox, each with its own help article.
01
Eleven named types
The pricing page lists Gmail (G Suite, OAuth), Outlook (Microsoft 365), Yahoo, iCloud, AOL, Yandex, Zoho, Sendgrid, Sendinblue, Mailgun and Amazon SES.
warmbox.ai/pricing · read 21 October 2026
02
Any other inbox
"Any other Inbox (SMTP)" is listed as well.
warmbox.ai/pricing · read 21 October 2026
03
A help article each
The "Add a new inbox" collection has 14 articles, including one for each provider and one for SMTP.
help.warmbox.ai/en/collections/2725610-add-a-new-inbox · read 21 October 2026
04
Third-party app password
"Third-party app Password" is listed under account features, and the Gmail article recommends an app password for stability.
help.warmbox.ai/en/articles/4803431-add-a-gmail-google-workspace-inbox · read 21 October 2026
05
Settings for each provider
Each of the 11 named types has its own help article, such as Add a Zoho inbox and Add an Amazon SES inbox.
help.warmbox.ai/en/collections/2725610-add-a-new-inbox · read 22 October 2026
06
Two Gmail routes
The help centre has one article for Gmail with Google sign-in and one for Gmail with credentials over SMTP.
help.warmbox.ai/en/collections/2725610-add-a-new-inbox · read 22 October 2026
07
Sending services as inbox types
Sendgrid, Sendinblue, Mailgun and Amazon SES are listed as inbox integrations, which suggests warming a sending-service address.
warmbox.ai/pricing · read 22 October 2026
08
Troubleshooting for Mailgun
The Quick Troubleshooting collection has an article for Mailgun connection issues alongside paused-campaign and token-expiry articles.
help.warmbox.ai/en/collections/18666827-quick-troubleshooting · read 22 October 2026
09
Provider pages on the site
The site has a Warmup page for each of Google, Outlook, Yahoo, iCloud, AOL, Yandex, Zoho, Sendgrid, Sendinblue, Amazon SES and any SMTP inbox.
warmbox.ai · read 22 October 2026
10
Same network for all
Its network is described as a mix of providers. It does not say whether every inbox type gets the same network.
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.
- Per-provider daily limits
- Whether every named type has the same warm-up network
- Daily sending limits for each named provider
- Whether the same network is used for Yahoo, iCloud and AOL
- Whether warm-up for Sendgrid or Mailgun inboxes works on shared sending IPs
Where the sources disagree
We report each version rather than pick one.
- Warmbox's pricing page names 11 inbox types, while its Add a new inbox collection lists 14 articles. The collection includes an overview article and a second Gmail method, so the counts differ without a conflict in what is supported.
The numbers
Only what we could verify.
| Measure | Warmerly | Warmbox |
|---|---|---|
| Inbox types supported | Gmail, Google Workspace, Microsoft 365 and other IMAP and SMTP mailboxes. | Gmail, Outlook, Yahoo, iCloud, AOL, Yandex, Zoho, Sendgrid, Sendinblue, Mailgun and Amazon SES, plus any SMTP inbox. |
| Named inbox types | Gmail, Google Workspace, Microsoft 365 | 11 named |
| Any SMTP inbox | Yes, over IMAP and SMTP | Yes |
| Zoho | Daily cap of 25 a day | Named |
| Preset connection forms | 5 | 11 named, plus SMTP |
| Gmail connection | Google app password | Google sign-in or app password |
| Microsoft connection | Microsoft sign-in | Outlook 365, method not stated on the pages read |
| Gmail daily cap in warm-up | 40 | Not stated |
| Outlook daily cap in warm-up | 30 | Not stated |
| Yahoo, iCloud, AOL, Yandex | Through custom SMTP and IMAP only | Named, with help articles |
| Sending-service inboxes | Not named | Sendgrid, Sendinblue, Mailgun, Amazon SES |
| Per-provider help articles | Guides for connecting and troubleshooting | 14 in the Add a new inbox collection |
In practice
What it means for you.
Our reading of the facts above. Not a promise, and not the only reasonable reading.
Check your own provider
If you warm Yahoo, iCloud, AOL, Yandex or Amazon SES inboxes, Warmbox names them. Ask Warmerly before you assume those work as well.
Most B2B senders are on Google or Microsoft
Both tools cover those two.
Look at where your mailboxes live
If most are on Google Workspace or Microsoft 365, both tools cover you and the difference is the connection route.
Test the one odd mailbox
If you have a Yahoo or iCloud address, connect it on a free Warmerly mailbox through custom SMTP and IMAP before you commit, or check Warmbox's help article.
Plan for app passwords
Both tools lean on a Google app password for stability, so turn on 2-Step Verification before you start.
Keep provider caps in mind
Warmerly holds Gmail to 40 a day and Outlook to 30 in warm-up. Warmbox says its own limit depends on the provider but publishes no figures.
Who it suits
Pick the one that fits.
Warmerly
Warmerly is the better fit if
- Your mailboxes are on Gmail, Google Workspace or Microsoft 365
- Your mailboxes are Google Workspace, Microsoft 365, Zoho or Namecheap
- You want the connection tested in both directions before it is saved
- You want published daily caps per provider
- You are happy to use custom SMTP and IMAP for anything else
Warmbox
Warmbox is the better fit if
- You warm Yahoo, iCloud, AOL, Yandex, Sendgrid, Sendinblue, Mailgun or Amazon SES inboxes
- You want a help article for each provider
- You warm Yahoo, iCloud, AOL, Yandex, Sendgrid, Sendinblue, Mailgun or Amazon SES inboxes
- You want a separate help article for each provider
- You want a Gmail sign-in route as well as an app password
- You want a site page per provider
Questions
Which inboxes does Warmbox support?
Gmail, Outlook, Yahoo, iCloud, AOL, Yandex, Zoho, Sendgrid, Sendinblue, Mailgun and Amazon SES, plus any inbox over SMTP.
Can Warmerly connect Yahoo or iCloud?
Only through custom SMTP and IMAP. It has 5 preset connection forms.
How is Gmail connected?
Warmerly uses a Google app password. Warmbox offers Google sign-in or an app password.
What are the daily warmup caps by provider?
Warmerly caps Gmail at 40, Outlook at 30 and Zoho at 25 a day. Warmbox does not state them.
Sources
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.
Free plan, no card. Paid plans: 7-day trial, first charge on day 8.