The Reply.io playbook

Reply.io runs the sequences. Your domain still has to earn the inbox.

Reply.io sends through the Gmail, Outlook, Exchange or other mailboxes you connect, and its MailToaster service warms each mailbox. The domain those mailboxes share carries a reputation of its own. Keep every sequence where it is. Add the domain here and we build its reputation while Reply.io keeps sending.

Start warming my domainSee Inbox Boost
The Reply.io playbook

Keep sending from Reply.io. Warm the domain here.

Step 1

Connect and authenticate your mailboxes

Gmail and Outlook connect in a single click, Exchange through EWS, and anything else as IMAP and SMTP; free addresses such as gmail.com or outlook.com are refused as senders. Reply.io cannot issue DKIM values: SPF, DKIM and DMARC come from your mail provider, and the Email Health Checker shows what is missing.

Step 2

Know what MailToaster does

MailToaster is Reply.io’s built-in warm-up service, with one warm-up seat per connected mailbox. It sends simulated positive engagement across providers such as Gmail, Outlook and Yahoo, and Reply.io says warm-up builds on top of correct MX, SPF, DKIM and DMARC rather than replacing them.

Step 3

Add your sending domain to Inbox Boost

Add the domain your mailboxes send as, the one in your From address, such as outreach.yourbrand.com, and we build its sender reputation for you, alongside MailToaster. Nothing to connect: no API key, no app, no mailbox sign-in, no change to your Reply.io account.

Step 4

Keep every sequence running in Reply.io

Sequences, steps and mailbox settings all stay in Reply.io. Mailbox providers score the domain in your From address, so the reputation built here counts for every mailbox sending as outreach.yourbrand.com.

Step 5

Check where Reply.io mail lands

Inbox placement tests show whether your sequence emails reach Primary, Promotions or Spam across the major mailbox providers, and blacklist monitoring keeps watching the domain once it is warm.

  • Nothing to connect: no Reply.io API key, app, integration or mailbox sign-in
  • Nothing to change: sequences, mailboxes and MailToaster stay exactly as they are
  • Every mailbox on the domain: the reputation belongs to the domain, so it counts for each mailbox sending from it
  • Watched after warmup: blacklist and authentication monitoring on your sending domain
Features Reply.io senders lean on

The parts of the platform this plan leans on.

Feature

Inbox Boost

Add a domain. We provision the sending server and publish your DNS.

Learn more Feature

Inbox placement testing

See whether you land in Primary, Promotions or Spam across providers.

Learn more Feature

Blacklist monitoring

45+ blacklist & reputation sources, scored 0-100 with trend history.

Learn more
See it play out

A Reply.io domain, warmed without pausing a single send.

Four checkpoints, in order. Click any step or let it play.

reply.io · outreach.yourbrand.com
SPF, DKIMpass
DMARCpublished
domain historynone yet
Questions

Reply.io questions, answered.

Does Inbox Boost connect to my Reply.io account or mailboxes?
No. There is no API key, app or integration to install, and nothing signs in to your Gmail, Outlook or Exchange mailboxes. Inbox Boost works on the sending domain, and Reply.io keeps sending your sequences exactly as it does now.
MailToaster already warms my mailboxes. Why warm the domain too?
MailToaster works on each connected mailbox, one warm-up seat at a time. Mailbox providers also score the domain those mailboxes share, and Inbox Boost works on that domain itself, alongside MailToaster. Reply.io advises keeping warm-up running while a mailbox sends cold email, and nothing here changes that.
My domain fails Reply.io’s Email Health Checker. What first?
Fix the records at your mail provider and DNS host. The most common failure Reply.io reports is two SPF records on one domain, which invalidates both. Reputation builds on authentication, so get SPF, DKIM and DMARC passing, then add the domain here.
What do Gmail and Outlook expect from my domain?
Authentication from your mail provider: SPF and DKIM, plus a DMARC record aligned with them. Gmail and Outlook both require all three from bulk senders, and Gmail counts mail from a primary domain and its subdomains together.
Can I see whether it is working?
Yes. Inbox placement tests show where your Reply.io sequence emails land, Primary, Promotions or Spam, across the major mailbox providers, and blacklist monitoring keeps watching the domain afterwards.
About the Reply.io facts on this page

Checked against Reply.io's own documentation on 12 October 2026. Reply.io is a trademark of its owner; SenderSignal is not affiliated with it.

Other cold outreach: Instantly, Smartlead, Lemlist, Apollo, Woodpecker. All use cases.

Reply.io keeps sending

Warm the domain behind your Reply.io sequences.

Start free, add the domain, and keep every sequence running in Reply.io while its reputation builds.

Start freeHow Inbox Boost works