Updated February 3, 2026

TL;DR: AT&T requires a Secure Mail Key instead of your regular password for third-party email clients. For IMAP (multi-device): Server imap.mail.att.net, Port 993, SSL enabled. For SMTP (outgoing): Server smtp.mail.att.net, Port 465 or 587, SSL required. Gmail's POP3 import feature ends in Q1 2026, making direct Gmail fetch no longer possible. If managing multiple AT&T accounts for outreach, skip manual client configuration and use a centralized solution like Instantly's Unibox to handle unlimited inboxes with automated warmup in one dashboard. For a deeper dive into cold email performance and best practices, check out our Cold Email Benchmark Report 2026.

Stop wasting time guessing port numbers. AT&T updated its security protocols in recent years, so your standard login password no longer works with Outlook, Apple Mail, or other third-party apps. You need one mandatory security step and specific server settings to fix it.

This guide provides the exact SMTP, IMAP, and POP3 configurations you need, plus solutions to the authentication errors that block most users. If you manage multiple accounts for lead generation or agency work, I'll show you why manual client setup creates friction and how to centralize reply management instead.

AT&T email server settings: The complete reference guide

Copy these settings directly into your email client. All configurations require SSL/TLS encryption and your full email address as the username.

You can use these settings for all AT&T legacy domains, including @att.net, @sbcglobal.net, @bellsouth.net, @ameritech.net, @flash.net, @nvbell.net, @pacbell.net, @prodigy.net, @snet.net, @swbell.net, @wans.net, and @currently.com.

Critical note on Yahoo servers: While AT&T email runs on Yahoo infrastructure, do not use Yahoo-branded servers like imap.mail.yahoo.com or pop.att.yahoo.com. Stick to the official att.net server addresses to avoid authentication redirects and connection timeouts.

Watch this complete Instantly setup walkthrough to see how streamlined email account management works when you move beyond manual client configuration.

Step 1: Create a secure mail key

The number one reason AT&T email connections fail is simple. Users enter their account login password when the system requires a 16-character secure mail key instead.

Follow these exact steps to generate your key:

1. Sign in to your account
2. Navigate to Profile, then select Sign-in info
3. Scroll to the Secure mail key section and select Manage secure mail key
4. If you have multiple email addresses, select the one you want to configure
5. Select Add secure mail key
6. Enter a nickname for the key, such as "Outlook Desktop" or "Apple Mail"
7. Select Create secure mail key
8. Copy the key to your clipboard immediately

The key displays only once. Write it down or paste it into a secure note. If you lose it, repeat these steps to generate a new one.

For growth marketers managing multiple accounts, this manual process multiplies fast. One user shared:

"I found setting up Instantly challenging for certain types of emails, requiring multiple steps for integration, especially with Google Workspace, which involved several steps before adding it to Instantly." - Eli A. on G2

While initial setup takes effort, the unified email dashboard centralizes all inboxes afterward, eliminating the need to generate keys and configure ports for every new account.

Step 2: Choose your protocol (IMAP vs. POP3)

Your protocol choice determines how email syncs across devices. Most users should choose IMAP.

IMAP syncs messages across your phone, laptop, and tablet so actions like reading or deleting appear everywhere, unlike POP3, which downloads email to one machine and typically removes it from the server. Learn more about POP3 and IMAP here.

Recommendation for growth marketers: Choose IMAP. Microsoft notes that IMAP keeps messages synced across multiple devices, making it easier to manage emails on phones, laptops, and tablets. For testing subject lines and tracking replies, you need that sync reliability.

Step 3: Configure AT&T email on Outlook

These instructions work for Outlook 2016, 2019, 2021, and Microsoft 365 desktop versions. Several older Outlook versions don't support OAuth for IMAP/POP3 accounts, which is why the Secure Mail Key is mandatory.

Follow these exact steps to connect your AT&T account:

Outlook setup steps:

1. Open Outlook, select File from the top menu, then choose Add Account
2. Enter your full AT&T email address (e.g., [email protected])
3. Select Advanced options, then check the box for "Let me set up my account manually"
4. Choose your protocol: Select IMAP (recommended) or POP
5. Fill in the incoming mail server settings:
   • IMAP Server: imap.mail.att.net
   • Port: 993
   • Check "This server requires an encrypted connection (SSL/TLS)"
6. Fill in the outgoing mail server settings:
   • SMTP Server: smtp.mail.att.net
   • Port: 465 (or try 587 if 465 fails)
   • Check "This server requires an encrypted connection (SSL/TLS)"
7. Authentication: In the password field, paste your Secure Mail Key, not your login password
8. Select More Settings, navigate to the Outgoing Server tab
9. Check the box for "My outgoing server (SMTP) requires authentication"
10. Select "Use same settings as my incoming mail server"
11. Click OK, then Next to test the connection

If Outlook shows "Testing Account Settings" and all items display green checkmarks, you're connected. One user shared:

"The setup of Instantly was incredibly straightforward, taking no more than thirty minutes, which I find very impressive. The platform is user-friendly and has been consistently reliable without any glitches, making my experience seamless and time-efficient." - Adnan k. on G2

For additional SMTP configuration guidance, including Microsoft-specific troubleshooting, check the platform's help documentation.

Step 4: Configure AT&T email on Gmail

Critical update: Google ends POP3 import functionality in Q1 2026. The "Check mail from other accounts" feature will no longer work for AT&T or any other third-party email provider. According to an Off The Peg Design analysis, both Gmailify and POP-based imports stopped functioning on January 1, 2026.

Your options for accessing AT&T email:

1. Use AT&T webmail at currently.att.yahoo.com directly in your browser
2. Configure a desktop client like Outlook or Thunderbird using the steps above
3. Connect AT&T accounts to Instantly and manage all replies in the Unified inbox dashboard

For growth marketers juggling multiple sender accounts, Gmail's limitation highlights why platform consolidation matters. Instead of configuring 10 AT&T accounts across separate clients, connect them once to a unified dashboard that handles warmup, reputation monitoring, and reply classification automatically.

A user managing multiple inboxes explained the benefit:

"I find Instantly incredibly beneficial for centralizing all my inboxes, which has notably streamlined my workflow, especially since I manage both MSF and Google inboxes. The platform allows me to check my inboxes from a single location without needing to log into each one individually, which saves me a lot of time." - Eli A. on G2

Troubleshooting authentication and connection errors

Most AT&T email errors come from three root causes. Here's how to fix each one.

Error: "Password incorrect" or "Authentication failed"

Cause: You entered your AT&T account password instead of the Secure Mail Key.

Fix:

1. Generate a new Secure Mail Key following the Step 1 instructions above
2. Delete the old password from your email client's saved credentials
3. Paste the new 16-character key into the password field
4. Ensure you're using your full email address ([email protected]) as the username

According to AT&T's official support guidance, if you recently changed your password or linked your email to your AT&T user ID, you must update credentials on all devices.

Error: "Cannot connect to server" or "Connection timeout"

Cause: Wrong server names, incorrect port numbers, or missing SSL/TLS encryption.

Fix:

1. Verify incoming server: For IMAP use imap.mail.att.net (not imap.mail.yahoo.com)
2. Verify outgoing server: For SMTP use smtp.mail.att.net (not smtp.att.yahoo.com)
3. Check ports: IMAP uses 993, POP3 uses 995, SMTP uses 465 or 587
4. Confirm SSL/TLS is enabled in your client's security settings
5. Test your internet connection by visiting att.com in a browser

Error: "Sending failed" or "SMTP error"

Cause: Incorrect SMTP port or authentication settings.

Fix:

1. Switch SMTP ports: If 465 fails, try 587 (or vice versa). Both ports support SSL/TLS but some networks block specific ports
2. Enable SMTP authentication: Ensure "My outgoing server requires authentication" is checked
3. Match credentials: Use the same Secure Mail Key for both incoming and outgoing servers

For marketers running campaigns, SMTP errors compound fast. If one inbox fails mid-sequence, replies drop and prospects slip through. One user noted:

"Good deliverability, easy spin tax, can add in lots of personalization clean and simple UI, one click email responses using tags, smooth Zapier integration, and powerful tracking with subsequences." - Joshua Blacklidge on Trustpilot

Watch this deliverability troubleshooting guide for advanced diagnostics on inbox placement and sender reputation issues that manual clients can't detect.

Managing multiple accounts? Stop using standard email clients

If you're an agency operator or growth marketer, configuring five or ten AT&T accounts in Outlook wastes time. Each account requires a separate Secure Mail Key, manual port entry, and isolated inbox management. Outlook doesn't warm cold domains, detect spam placement, or centralize replies across accounts.

Here's what breaks at scale:

Data isolation: Each Outlook profile operates independently. You can't track A/Z test variants or export unified analytics across accounts.

No reputation protection: Instantly's automated warmup network of 4.2M+ accounts gradually builds engagement signals for legacy AT&T domains. Outlook sends cold emails from cold domains, landing you in spam.

Manual reply triage: When 10 inboxes each receive 50 replies per day, sorting interested prospects from out-of-office messages and unsubscribes wastes hours. One user running campaigns explained:

"the fact that emails actually land in main inboxes as well as the unibox with its alerts that allow my team to focus only on positive replies - this saves so much time and human labor." - Idan s. on G2

Credit and cost predictability: Adding accounts to Outlook is free but scales poorly. When you need to test send windows, run sequence variants, or handle bounce management, you're stitching together third-party tools. Instantly includes unlimited email accounts on flat-fee pricing, which eliminates per-seat taxes as you grow.

How Instantly simplifies multi-account workflows:

1. Connect unlimited accounts: Add AT&T, Gmail, Outlook, and custom SMTP inboxes to one dashboard using the IMAP/SMTP connector guide
2. Automated warmup: Every connected inbox enters the deliverability network automatically, building sender reputation before you send cold emails
3. Unibox: All replies from all accounts appear in one centralized inbox with AI-powered classification
4. Monitor bounce and blocklist protection: The platform tracks global blocklists and pauses sending if domain health drops

A user managing long-term campaigns shared results:

"Instantly is an excellent platform for email marketing outreach. I've been using it for over two years, have recommended it to many clients, and we've all had great results." - Muhammad Auoon on Trustpilot

If you're ready to stop configuring Outlook profiles and start scaling outreach, try Instantly to connect your accounts in minutes and let automation handle warmup while you focus on messaging and conversion.

For a complete walkthrough, watch our full platform tutorial covering account setup, campaign creation, and reply management.

Frequently asked questions

What is the incoming mail server for AT&T email?
For IMAP use imap.mail.att.net on port 993. For POP3 use inbound.att.net on port 995.

Do I need a Secure Mail Key for Outlook?
Yes. Some older versions of Outlook lack OAuth support for IMAP/POP3, making the Secure Mail Key mandatory.

Can I use Yahoo server settings for AT&T email?
No. Use official att.net servers to avoid authentication redirects.

Why did Gmail stop fetching my AT&T email?
Google ends POP3 import in the first quarter of 2026. Use AT&T webmail, configure a desktop client, or connect accounts to a unified platform instead.

Which SMTP port should I use, 465 or 587?
Both work. Port 465 uses implicit SSL, while 587 uses STARTTLS.

Does IMAP delete emails from the server?
No. IMAP stores messages on the server and syncs across devices.

Key terminology

SMTP (Simple Mail Transfer Protocol): The protocol that sends email between clients and servers. AT&T's SMTP server is smtp.mail.att.net on ports 465 or 587.

IMAP (Internet Message Access Protocol): The protocol that retrieves and syncs email across multiple devices by storing messages on a remote server.

POP3 (Post Office Protocol version 3): A protocol that downloads messages to a single device and removes them from the server.

SSL/TLS (Secure Sockets Layer / Transport Layer Security): Encryption that secures the connection between your email client and the server.

Port: A numbered endpoint that identifies which application or service on a server handles the connection. IMAP uses 993, POP3 uses 995, SMTP uses 465 or 587.

Secure Mail Key: An authentication code generated in myAT&T that replaces your account password for third-party email clients. You need it for Outlook, Thunderbird, Apple Mail, and other non-OAuth apps.