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Connect any inbox via SMTP/IMAP

Add a non-Google/Microsoft mailbox with server credentials. Test the connection, then send and read replies through it.

Tutorials
Mailboxes
min read
7 min
steps
8 · Intermediate

  1. Connectors → Add Connector → SMTP / IMAP

    Open Connectors from the left nav and click Add Connector. Pick SMTP / IMAP for any provider that isn't Google or Microsoft: Zoho, Fastmail, a private mail server, or a cPanel host.

    Connectors → Add Connector → SMTP / IMAP

  2. Choose the Single Account tab

    SMTP / IMAP opens a two-tab panel: Single Account and Bulk Upload (CSV). Stay on Single Account to connect one mailbox: use Bulk Upload if you're adding many at once.

  3. Enter credentials

    Fill in Email address, an optional Display name, Username, and Password (use the eye icon to double-check what you typed). Username is often the full email address, but check your provider's docs if the login differs.

  4. Set Outgoing (SMTP)

    In Outgoing (SMTP), enter your SMTP host, pick a SMTP port (587, 465, 25, 2525, or Custom), and set SMTP encryption (TLS, SSL, or None). The default is 465 / SSL.

  5. Set Incoming (IMAP)

    In Incoming (IMAP), enter your IMAP host, IMAP port (993 or 143), and IMAP encryption. The default is 993 / TLS. IMAP is required so FirstSales can read replies and route them to your inbox.

  6. Click Test connection

    You must pass Test connection before you can save. A success shows “Connection verified: ready to save.” A failure almost always means a wrong host/port, or that your provider requires an app-specific password.

  7. Click Add account

    Once verified, click Add account. A toast confirms “Email account added!” and the mailbox now appears in Connectors.

  8. Warm it up before real sends

    A new mailbox has no reputation. Open its Warm Up tab and turn on warm-up before pointing real campaigns at it: see the email warm-up tutorial for the full walkthrough.

    Warm it up before real sends

Pro tips

  • App passwords, not your login password

    Most providers (Zoho, Fastmail, iCloud, Gmail-via-SMTP) require a generated app-specific password when 2FA is on. If Test connection fails on a correct host/port, this is almost always why.

  • Match port to encryption

    465 = SSL, 587 = TLS/STARTTLS, 25 = None. The form auto-fills a sensible default port when you switch encryption: only override it if your provider documents a non-standard one.

  • Don't skip IMAP

    SMTP alone would send but never see replies. Give the IMAP host and port so reply detection, stop-on-reply, and the inbox all work.

  • The test gate is a feature

    You can't save an untested mailbox by design: a bad credential surfaces here instead of silently failing mid-campaign.

Frequently asked questions

When should I use SMTP/IMAP instead of Google/Microsoft?

Use OAuth (Google/Microsoft) when your inbox is on either of those. Use SMTP/IMAP for every other provider: Zoho, Fastmail, private or cPanel mail, and similar hosts.

Why do I need both SMTP and IMAP?

SMTP sends mail; IMAP lets FirstSales read replies so stop-on-reply and the inbox work.

What port and encryption should I use?

465/SSL or 587/TLS for SMTP, and 993/TLS for IMAP are the common choices. The form defaults to 465/SSL and 993/TLS.

Test connection keeps failing: what's wrong?

Usually an app password is required because 2FA is on, or the host/port/encryption combination is wrong. Verify against your provider's SMTP/IMAP documentation.

Is my password stored safely?

Credentials are stored so FirstSales can send and read mail on your behalf. Unlike OAuth there's no revocable token, so use an app-specific password you can revoke on the provider's side.

Can I add many SMTP mailboxes at once?

Yes: switch to the Bulk Upload (CSV) tab to import several mailboxes from a spreadsheet (covered in the bulk-import tutorial).

Can I connect a personal Gmail this way?

Technically yes, with an app password: but Google OAuth is cleaner, and cold outreach should send from your own domain regardless.

Do I still need to warm it up?

Yes. Connecting is step one: enable warm-up on the Warm Up tab before you rely on the mailbox for real sends.

Mailboxes

Outreach that keeps going after you log off.Leads, emails, follow-ups and replies, handled.

Connect unlimited mailboxes and let AI agents find leads, write each email and follow up. Or send your own templates in manual mode. From $29/mo.

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Install with AI

Your coding agent sets up the FirstSales CLI and skills for you.

Prompt for Claude Code

I'm setting up FirstSales (https://firstsales.io), an AI outbound sales platform: campaigns, contacts, a reply inbox, deliverability and lead signals. Help me get my workspace sending real, good emails end to end, from Claude Code.

Read these first so you know how FirstSales works:
- Developer docs and API: https://developer.firstsales.io
- CLI: https://www.npmjs.com/package/@firstsales.io/cli
- Skills for coding agents: https://github.com/firstsalesio/firstsales-skills (read README.md and GUIDE.md)

Setup
1. Install the CLI: npm install -g @firstsales.io/cli
2. Install the FirstSales skills:
   claude plugin marketplace add firstsalesio/firstsales-skills
   claude plugin install firstsales@firstsales
3. Ask me if I already have a FirstSales account. If not, send me to https://app.firstsales.io to sign up.
4. Ask me to create an API key under Settings → API → API Keys, with only the scopes we need.
   Never ask me to paste the key into this chat. Tell me to run this in my own terminal, so the key stays hidden:
   read -rs FS_KEY && firstsales auth login --api-key "$FS_KEY"; unset FS_KEY
5. Run `firstsales whoami` and tell me which workspace and organisation we are connected to.

Then ask me about my business: what I sell, who I sell to (roles, company size, countries), my best customers, and what I use today for outbound (tools, lists, mailboxes). Walk me through:
1. Teaching FirstSales my business: website, offer, proof points and case studies in the knowledge base, so the AI writes like someone who knows the product.
2. Connecting my sending mailboxes and checking my sending domain: SPF, DKIM, DMARC and warm-up. If anything is unhealthy, tell me the exact DNS record to add.
3. Bringing in contacts: import my CSV or CRM export into a clean list, remove duplicates and bad emails, and block domains I must never email (customers, competitors, my own).
4. Building my first campaign: the right list, senders, steps and timing. Write the sequence with me, show me the drafts, and do not launch until I say yes.
5. Setting up Signals if it fits: find people engaging with LinkedIn posts about topics my buyers care about, and turn them into leads.
6. Inviting my team and giving each person the right access.

Once campaigns run, show me how to work the reply inbox from here: which replies need an answer, draft responses in my voice, and move good conversations into deals. If I use Cal.com, connect it so follow-ups can offer my booking link (not the first email).

Throughout, as you learn about my business, proactively suggest and help create:
- Reply templates for the questions and objections my prospects are likely to raise, based on my product, site and codebase if you can see them.
- Campaign ideas and segments worth testing, with the reason for each.

Safety rules:
- Show every change as a dry run (--dry-run) first and wait for my yes. Never send emails, launch campaigns or delete anything without my yes.
- Tell me before anything that spends credits, and how many.

Be opinionated. If the docs give a sensible default, just use it. Don't make me choose between five options.
Developer docs ↗npm: @firstsales.io/cli ↗GitHub: firstsales-skills ↗