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SMTP App Password Settings: Yahoo, AOL, iCloud, GMX

Updated 2026-10-03 · by Adam Hale

This page lists the SMTP server, port, security mode and app-password rules for Yahoo, AOL, AT&T, iCloud, GMX, Web.de, Fastmail and Zoho, taken from each provider's official help pages on 2026-10-03. The pattern is the same almost everywhere: port 465 with SSL/TLS or port 587 with STARTTLS, your full email address as the username, and an app password instead of your normal password.

SMTP settings by provider

Provider SMTP server Port and security Username Password
Yahoo smtp.mail.yahoo.com 465 SSL/TLS, or 587 Full address Yahoo app password
AOL smtp.aol.com 465 SSL/TLS Full address AOL app password
AT&T (att.net, sbcglobal.net, bellsouth.net…) smtp.mail.att.net 465 or 587 Full address 16-character secure mail key
iCloud smtp.mail.me.com 587, STARTTLS Full iCloud address App-specific password
GMX (gmx.com) mail.gmx.com 587 STARTTLS, or 465 SSL/TLS Full address GMX password; enable POP3/IMAP access first
GMX (gmx.net, gmx.de) mail.gmx.net 587 STARTTLS, or 465 SSL Full address Same as above
Web.de smtp.web.de 587 STARTTLS, or 465 SSL Full address Web.de password; enable POP3/IMAP access first
Fastmail smtp.fastmail.com 465 SSL/TLS, or 587 STARTTLS Full address Fastmail app password
Zoho, paid plan with your domain smtppro.zoho.com (US data center) 465 SSL, or 587 TLS Full address Password, or app-specific password with 2FA
Outlook.com / Hotmail smtp-mail.outlook.com 587 — OAuth only; app passwords don't work

Zoho's host differs by data center; Zoho shows yours under Settings, then Mail Accounts. Zoho's free plan is web-only, and new free users don't get IMAP access. For Outlook.com, see the Outlook and Hotmail guide.

SMTP app password steps for Yahoo, AOL, iCloud and GMX

Yahoo

  1. Sign in to your Yahoo Account Security page.
  2. Under "External connections", click Create app password.
  3. Name it, click Generate password, and copy it.

Yahoo says to use "a browser that you've used to sign into Yahoo for several days in a row and avoid using Incognito mode", and that "Customer care can't override" a refusal. App passwords survive a change of your main password; delete them to revoke.

AOL

AOL works the same way as Yahoo. You create the app password from your AOL account security page, and it stays active until you delete it (AOL Help).

AT&T

Go to your AT&T account profile, choose Settings, then Add secure mail key. Give it a nickname and copy it. AT&T says to create a separate key for each AT&T address and subaccount, and it deletes keys if your account is locked or blocked.

iCloud

Your Apple Account needs two-factor authentication.

  1. Sign in at account.apple.com.
  2. Under Sign-In and Security, select App-Specific Passwords.
  3. Generate one and paste it into your app.

You can have up to 25 active. Apple revokes all of them when you change or reset your Apple Account password. Apple's settings page also says that if SSL gives an error on port 587, you should try TLS or STARTTLS.

GMX and Web.de

POP3/IMAP access is off by default. In GMX, go to Email, then Settings, then POP3 & IMAP, and tick "Enable access to this account via POP3 and IMAP". GMX notes that it turns this setting off again "if you do not use POP3/IMAP for a longer period of time." Web.de has the same switch, under POP3/IMAP Abruf. (not yet confirmed) With two-factor authentication on, both reportedly require an app password instead of your normal one.

Fastmail

Go to Settings, then Privacy & Security, then Manage app passwords and access, then New app password. Fastmail's Basic plan does not include IMAP or SMTP, so you need Individual ($60/yr) or higher.

Zoho

Go to Zoho Accounts, then Security, then Application Specific Passwords, then Generate New Password. Zoho shows it only once.

Common errors and fixes

Symptom Likely cause
"535 authentication failed" You used your normal password instead of an app password, or a username without the domain
The connection hangs, then times out Port and security mode don't match. 465 expects TLS from the start; 587 starts plain and upgrades with STARTTLS
GMX or Web.de rejects the login POP3/IMAP access is switched off, or was switched off automatically
Yahoo won't offer an app password Eligibility check; try a browser you use regularly, not Incognito
iCloud stopped working You changed your Apple Account password, which revokes app-specific passwords
Port 25 refused Port 25 is for server-to-server mail, not for submitting your own messages

Keep app passwords contained

How SendAs Relay fits

SendAs Relay uses exactly these settings. You enter the SMTP server, port, username and app password for each address you want in Gmail's From menu. When you send, a stateless relay opens one SMTP session to that server and forwards your message.

It's not the right fit for Outlook.com/Hotmail, for Proton Mail (which offers SMTP only through its local Bridge app), on Chrome, or in the Gmail mobile apps. There, a desktop client or the provider's own app is the better choice. Details: security and how it works.

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