Mailbird’s onboarding wizard handles Gmail and Outlook.com with one-click OAuth — but if you’re adding a corporate IMAP account, a custom domain, or troubleshooting a sync failure, you need the exact settings. This guide covers the IMAP/SMTP configuration for Gmail, Outlook.com, and custom accounts, plus the common errors and how to fix them.
Download MailbirdAdd Gmail via IMAP
Gmail IMAP requires two steps before Mailbird can connect: (1) enable IMAP in Gmail Settings, and (2) use OAuth (preferred) or generate an App Password if you have 2-factor authentication enabled.
Step 1: Enable IMAP in Gmail
- Open Gmail in your browser and click the gear icon → See all settings
- Go to the Forwarding and POP/IMAP tab
- Under “IMAP access”, select Enable IMAP
- Click Save Changes
If IMAP is already enabled, skip to Step 2.
Step 2: Connect in Mailbird
Option A — OAuth (recommended):
- Open Mailbird and go to Settings → Accounts → + Add account
- Enter your Gmail address and click Continue
- Mailbird detects Gmail and shows an “Add Gmail account” button
- Click it — your browser opens a Google OAuth page
- Log in to Google, approve Mailbird’s access request
- Return to Mailbird — your Gmail inbox starts syncing
OAuth is the preferred method because it does not require your Google password or an App Password. Google generates a secure token that Mailbird stores locally.
Option B — App Password (required if OAuth fails or you prefer manual control):
If you have 2-Step Verification enabled and OAuth doesn’t work, use an App Password:
- Go to your Google Account → Security → 2-Step Verification → App passwords (at the bottom of the section)
- Select “Mail” and “Windows Computer” from the dropdowns, click Generate
- Google shows a 16-character password — copy it
- In Mailbird, add a new account, enter your Gmail address
- When prompted for a password, paste the 16-character App Password (not your Google account password)
- Set IMAP server:
imap.gmail.com, port993, SSL/TLS - Set SMTP server:
smtp.gmail.com, port587, STARTTLS (or port465, SSL/TLS)
Gmail labels in Mailbird
Mailbird displays Gmail labels as folders in the left sidebar. Labels you’ve created in Gmail appear as sub-folders. The “All Mail” label is accessible. Mailbird’s “Unified Inbox” combines messages from all connected accounts including Gmail, regardless of label structure.
Add Outlook.com via IMAP
Outlook.com (and Hotmail/Live) connect to Mailbird via OAuth or IMAP. OAuth is the easier path — Mailbird detects Outlook.com domains and offers the sign-in button automatically.
Via OAuth (easiest):
- In Mailbird, go to Settings → Accounts → + Add account
- Enter your Outlook.com (or Hotmail/Live) email address
- Mailbird detects it and shows a “Sign in with Outlook” button
- Click it — your browser opens a Microsoft login page
- Sign in to your Microsoft account, approve access
- Return to Mailbird — inbox syncs automatically
Via manual IMAP (if OAuth fails):
Per Microsoft’s IMAP documentation:
- IMAP server:
outlook.office365.com - IMAP port:
993 - Encryption: SSL/TLS
- SMTP server:
smtp-mail.outlook.com - SMTP port:
587 - SMTP encryption: STARTTLS
- Username: Your full Outlook.com email address
- Password: Your Microsoft account password (or App Password if 2FA is enabled)
Note on Microsoft 365 corporate accounts: Outlook.com (personal) differs from Microsoft 365 work accounts. For corporate M365, IMAP works but you may encounter conditional access policies requiring you to use Outlook or an Intune-enrolled app. If your IT team has blocked third-party IMAP clients, Mailbird will fail to connect. Mailbird does not support native EWS (Exchange Web Services) — for full Exchange feature support, see eM Client or Outlook.
Add a Custom IMAP Account
Custom IMAP accounts (custom domain email via cPanel, Fastmail, Zoho Mail, Proton Mail Bridge, or your own mail server) require manual IMAP/SMTP settings. Get the settings from your email host’s documentation.
General steps:
- In Mailbird, go to Settings → Accounts → + Add account
- Enter your custom email address
- If Mailbird cannot auto-detect the settings, it will show fields for manual entry
- Enter:
- Your name (display name in sent emails)
- Email address
- Password
- IMAP server (from your host’s documentation)
- IMAP port (usually 993 for SSL/TLS, or 143 for STARTTLS)
- IMAP security (SSL/TLS or STARTTLS)
- SMTP server
- SMTP port (usually 465 or 587)
- SMTP security (SSL/TLS or STARTTLS)
- SMTP username (often the same as your email address)
- SMTP password (same as IMAP password, usually)
Common hosting providers:
| Host | IMAP server | IMAP port | SMTP server | SMTP port |
|---|---|---|---|---|
| Fastmail | imap.fastmail.com | 993 | smtp.fastmail.com | 465 |
| Zoho Mail | imap.zoho.com | 993 | smtp.zoho.com | 587 |
| cPanel (shared hosting) | mail.yourdomain.com | 993 | mail.yourdomain.com | 587 |
| Posteo | posteo.de | 993 | posteo.de | 587 |
For hosts not in this table, search “[your host] IMAP settings” or check their support documentation. The exact server addresses vary — using the wrong server address is the most common cause of failed custom IMAP connections.
Proton Mail note: Proton Mail uses end-to-end encryption that is incompatible with standard IMAP. To use Proton Mail with Mailbird, you must install the Proton Mail Bridge app, which runs locally and exposes a local IMAP interface on 127.0.0.1. Mailbird then connects to the Bridge (not directly to Proton’s servers). This is more complex to set up but fully functional.
Quick Reference: IMAP/SMTP Settings
| Provider | IMAP server | IMAP port | SMTP server | SMTP port | Auth |
|---|---|---|---|---|---|
| Gmail | imap.gmail.com | 993 | smtp.gmail.com | 587 | OAuth or App Password |
| Outlook.com | outlook.office365.com | 993 | smtp-mail.outlook.com | 587 | OAuth or password |
| Yahoo Mail | imap.mail.yahoo.com | 993 | smtp.mail.yahoo.com | 465 | App Password required |
| iCloud Mail | imap.mail.me.com | 993 | smtp.mail.me.com | 587 | App-specific password |
| Fastmail | imap.fastmail.com | 993 | smtp.fastmail.com | 465 | Password |
| Zoho Mail | imap.zoho.com | 993 | smtp.zoho.com | 587 | Password |
Sources: Google, Microsoft, provider documentation.
Troubleshooting Sync Errors
The four most common Mailbird IMAP errors are: 2FA blocking IMAP (fix: App Password), IMAP disabled in provider settings (fix: enable it), wrong server address or port (fix: verify from provider docs), and rate limiting on initial sync (fix: wait or reduce sync frequency).
”Authentication failed” or “Invalid credentials”
Gmail: 2-factor authentication blocks direct password login. Solution: use OAuth (the preferred method) or generate an App Password at myaccount.google.com → Security → App passwords.
Yahoo Mail: Yahoo requires an App Password for third-party IMAP access regardless of 2FA status. Generate one at security.yahoo.com → Other apps (App passwords).
iCloud / Apple ID: iCloud Mail requires an app-specific password. Generate one at appleid.apple.com → Sign-In and Security → App-Specific Passwords.
”Cannot connect to server”
- Verify the IMAP server address exactly (no typos, no
https://prefix — just the hostname) - Verify the port number matches the security setting (993 = SSL/TLS, 143 = STARTTLS)
- Check if your email host has a maintenance status page
- Temporarily disable your firewall or VPN to see if it’s blocking port 993 or 587
- If using a corporate network, IMAP ports may be blocked by the network policy — test on a personal network or mobile hotspot
”Folder sync not working” on Gmail
Mailbird syncs the folders/labels you’ve subscribed to in Gmail. If a label is not appearing in Mailbird:
- In Gmail Settings → Labels, verify the label has “Show in IMAP” checked
- In Mailbird → Settings → Accounts → select the account → Folders → verify the label is subscribed
”Sent mail appears twice” on Gmail
This happens when Mailbird’s SMTP send is also saved to Gmail’s Sent folder by the server, while Mailbird is also placing a copy in its local Sent folder. Fix: in Mailbird → Settings → Accounts → select the Gmail account → uncheck “Store sent messages locally”. Gmail’s server-side copy in Sent is sufficient.
Slow initial sync on large mailboxes
Mailbird indexes messages locally on first sync. For large mailboxes (50,000+ messages), this can take 15–30 minutes. Leave Mailbird open and connected; the index build happens in the background. Full-text search is available after indexing completes.
Managing Multiple Accounts
Mailbird Premium supports unlimited IMAP accounts in a unified inbox. All accounts’ mail appears in a single inbox view. Account-specific folders are accessible in the left sidebar organised by account.
Adding a second (or third, or fifth) account follows the same process as the first: Settings → Accounts → + Add account. Each account syncs independently.
Unified inbox view: The default “All accounts” inbox view shows new messages from all connected accounts in one chronological feed. Each message is colour-coded by account (colours are customizable per account in Settings → Accounts → the account entry → choose colour).
Account-specific inbox: Click an account name in the left sidebar to view only that account’s inbox. Folder structure below each account is visible when you expand the account in the sidebar.
Signature per account: You can set different signatures for each account in Settings → Accounts → select account → Signature. When composing a new message, the “From” dropdown selects the sending account and the appropriate signature loads automatically.
Free vs. paid account limits:
- Mailbird Free: 1 IMAP account
- Mailbird Premium (paid): unlimited accounts
If you’re on the free tier and need a second account, you must upgrade. See our Mailbird pricing guide for the full breakdown.
Ready to set up multiple accounts? Download Mailbird — the free tier lets you test with one account before committing.
What IMAP Doesn’t Give You
IMAP access to corporate Exchange or Microsoft 365 accounts does not include Exchange-specific features: shared calendars, delegation, meeting rooms, Global Address List. For those, eM Client (EWS) or Outlook are more complete options.
IMAP is a standard email protocol — it covers sending and receiving mail, folder management, and search. It does not include:
- Exchange calendar and delegation: Shared calendars in Exchange/M365 require EWS or the native Exchange protocol. IMAP gives you mail only, not calendar. eM Client supports EWS natively.
- Global Address List (GAL): The company contact directory in Exchange is not accessible via IMAP. You’d need to manually export and import contacts, or use a client with native Exchange support.
- Out-of-office auto-reply from the server: You can set an out-of-office reply in Mailbird as a local auto-reply rule, but it requires Mailbird to be running. Setting the out-of-office on the Exchange server (visible to anyone, even when your computer is off) requires Exchange access.
- Push email on corporate Exchange: Some IMAP implementations on Exchange poll rather than push. Message delay of several minutes may occur on heavily throttled corporate Exchange IMAP configurations.
If you need these Exchange features and don’t want to use Microsoft Outlook, eM Client is the strongest alternative with native EWS support.
Also see: Mailbird setup guide, Mailbird review 2026, Mailbird pricing 2026.
Alexis Dollé, email expert for 10+ years. Founder of Email Tools. I test every email client and utility myself, then write about them the way I’d explain them to a friend — no marketing fluff, no sponsored rankings, every claim sourced.
LinkedInFrequently asked questions
What IMAP settings does Mailbird use for Gmail? — imap.gmail.com:993
Gmail IMAP server: imap.gmail.com, port 993, SSL/TLS. SMTP server: smtp.gmail.com, port 587 (STARTTLS) or 465 (SSL/TLS). Gmail requires OAuth (preferred) or an App Password if 2-factor authentication is enabled. See Google’s IMAP documentation for current settings.
Why is Mailbird not syncing my Gmail? — enable IMAP, then use OAuth or App Password
The most common causes: (1) IMAP is disabled in Gmail Settings → Forwarding and POP/IMAP → enable it. (2) 2-factor authentication blocking direct login — generate an App Password in your Google Account → Security → 2-Step Verification → App passwords. (3) Use OAuth in Mailbird’s account setup if you prefer not to use an App Password.
What IMAP settings does Mailbird use for Outlook.com? — outlook.office365.com:993
Outlook.com IMAP server: outlook.office365.com, port 993, SSL. SMTP server: smtp-mail.outlook.com, port 587, STARTTLS. Source: Microsoft documentation.
Does Mailbird support Exchange or Microsoft 365? — IMAP only, no native EWS
Mailbird connects to Microsoft 365 accounts via IMAP/OAuth. It does not support native Exchange EWS protocol. Exchange-specific features (shared calendars, delegation, GAL) are not available via IMAP. For full Exchange functionality, eM Client or Outlook are better options.
How many IMAP accounts can I add to Mailbird? — 1 free, unlimited paid
Mailbird Free supports one IMAP account. Mailbird Premium (paid, ~€27.60/year or €73.80 one-time) supports unlimited IMAP accounts with a unified inbox across all of them.
Can Mailbird connect to Proton Mail? — yes, via Proton Bridge
Yes, but it requires the Proton Mail Bridge app. Install Bridge, which exposes a local IMAP interface at 127.0.0.1. Then configure Mailbird to connect to that local server with the credentials Bridge provides. Direct IMAP to Proton’s servers is not supported because Proton uses end-to-end encryption incompatible with standard IMAP.