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Mail server settings

Yahoo Mail IMAP and SMTP settings

The incoming and outgoing servers for Yahoo Mail, the ports and security to pick, and which password a mail app needs. Type a different address to look up another provider.

The address stays in your browser. For a domain we don't know, only the domain name is sent to our server to read its MX records.

Yahoo Mail

yahoo.com

Known providerApp password required

Incoming · IMAP

Outgoing · SMTP

Also accepted: port 587 with STARTTLS. Authentication required.

Password

  • An app password generated in your account settings; never the account password. Create one →
  • Yahoo refuses the account password in mail apps unless the app supports Yahoo sign-in. Create an app password: Account Security → Generate and manage app passwords.
Yahoo Mail help pageSet up Yahoo Mail in Sickle
  1. Mail → Add Account… → Other Mail Account… (for Gmail, iCloud, Outlook.com and Yahoo pick the named option instead; it signs you in and skips the servers).
  2. Enter name, address, password → Sign In. Mail tries to detect settings; when it can't, the server fields appear.
  3. Paste the Incoming and Outgoing servers above, username as shown, and sign in.
  4. Ports and SSL are set automatically; to check them: Mail → Settings → Accounts → Server Settings and untick "Automatically manage connection settings".
How to read these

Two servers, four numbers, one password rule.

A mail app needs two servers. IMAP is the incoming server: it keeps your mail on the provider's computer and mirrors it to every device, so an archive on your Mac is an archive on your phone. SMTP is the outgoing server: it is the only thing that can send mail from your address. POP3 is the older incoming protocol that downloads and often deletes; almost nobody should pick it in 2026.

Ports and security, in one table

ProtocolPortSecurityUse it?Why
IMAP993SSL/TLS (implicit)YesEncrypted from the first byte. The default everywhere, and the only one some clients (Sickle included) accept.
IMAP143STARTTLS or noneOnly if 993 is missingStarts in plain text and upgrades. Fine when it upgrades, risky when it doesn't.
SMTP465SSL/TLS (implicit)YesModern submission port, re-standardised in RFC 8314. Encrypted from the start.
SMTP587STARTTLSYesThe classic submission port. Most providers offer both 465 and 587; pick whichever your app lists first.
SMTP25Usually noneNoServer-to-server relay. Blocked by most home ISPs and refused for client logins.
POP3995SSL/TLSRarelyDownloads mail to one device. Pick IMAP unless you have a reason.

Why your normal password gets rejected

Providers have been closing the plain-password door for years, each in their own way. Four patterns cover almost every "authentication failed" you'll see.

PatternProvidersWhat to do
Sign-in only (OAuth)Outlook.com, Hotmail, Live, Microsoft 365The app must support "Sign in with Microsoft". Passwords are refused outright since September 2024. Apple Mail, Thunderbird, Outlook and Sickle all qualify.
Sign-in preferred, app password allowedGmail, Google WorkspaceUse "Sign in with Google". Or turn on 2-Step Verification and create an app password at myaccount.google.com/apppasswords.
App password requirediCloud, Yahoo, AOL, Fastmail, Yandex, Mail.ruGenerate a one-off password in the account's security settings and paste that instead. Your real password will never work in a mail app.
Separate code or keyQQ Mail and 163 (authorization code), AT&T (Secure Mail Key), T-Online (E-Mail-Passwort)Same idea, different name. The provider generates it; you paste it as the password.
Common errors

When it still won't connect.

"Could not connect to the server" or a timeout

The host name or port is wrong, or you picked SSL/TLS on a STARTTLS port (or the reverse). Match the pairs exactly: 993 with SSL/TLS, 143 with STARTTLS, 465 with SSL/TLS, 587 with STARTTLS. On hotel and office Wi-Fi, port 25 and sometimes 587 are blocked; 465 usually isn't.

"Authentication failed" with a password you know is right

Most big providers no longer accept the account password from mail apps: Microsoft wants a sign-in, Apple, Yahoo, AOL and Fastmail want an app password, QQ and 163 want an authorization code. Check whether IMAP access is switched on in the provider's web settings too; Outlook.com, GMX, WEB.DE, Zoho, Yandex, QQ, Neo and Titan all ship with it off.

Receiving works but sending doesn't

Outgoing servers almost always need authentication now; make sure "use the same credentials as incoming" is ticked. Some ISPs (Comcast, Spectrum) require you to enable third-party access separately before SMTP will take your login.

The username field: whole address or just the name?

Whole address, with very few exceptions. If a provider wants only the part before the @, the result card says so. Some clients (Sickle, iOS Mail) only ever use the full address.

The domain is a company or a web host and nothing matches

Then your mail is hosted somewhere you may not expect. The tool reads the domain's MX record to find out. If it points at Google or Microsoft, use those settings with your work address. If it points at the web host, the server is usually mail.yourdomain.com and the exact names are in the hosting panel under Email Accounts.

Other providers

Settings by provider.

Or skip the lookup

Sickle already knows these.

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