Migrate AOL Mail to Outlook.com: The IMAP Field Guide

People hold on to AOL accounts for nostalgia, for an old friends list, and because the address has been the recovery contact on a hundred online accounts for two decades. Outlook.com is the practical replacement when Gmail does not suit and a paid Microsoft 365 mailbox feels like overkill. The free Outlook.com mailbox does most of what AOL used to do, with a better mobile app and a spam filter that has not been frozen in time since 2008. The catch is that getting twenty years of mail out of AOL and into Outlook.com is not the same job as setting up forwarding. Forwarding only catches new messages. To pull the history across with dates, folders, and read state intact, you need an IMAP migration. This guide walks through the full job, from generating an app password on the AOL side to verifying the result in Outlook.com, with the specific gotchas that catch people out on both ends. It assumes a single personal mailbox; the shape works for several mailboxes in sequence too.

Prerequisites#

Outlook.com no longer uses the same Connected Accounts feature that once made this a one-click affair. Microsoft retired the import pull for new accounts, which means you now need a desktop IMAP tool sitting between the two providers. Pick something that supports app-password authentication against AOL and either basic or OAuth authentication against Outlook.com.

You will need:

• The full AOL email address and an AOL app password generated in Account Security.
• An Outlook.com address you can sign in to. If you have not created one, do that first at outlook.com.
• The Outlook.com password, or a Microsoft account app password if you have enabled two-step verification on the Microsoft side.
• A workstation that can stay awake several hours.
• A stable network connection. Coffee-shop Wi-Fi will not finish a 10 GB run; expect repeated disconnects.

If you manage several family AOL accounts, generate a separate app password for each. Do not reuse credentials and do not run more than one or two migrations at the same time from the same machine; AOL throttles by source IP as well as by account.

Connection settings#

• AOL IMAP host: imap.aol.com
• AOL IMAP port: 993 (SSL/TLS)
• AOL credential: full address plus the app password
• Outlook.com IMAP host: outlook.office365.com
• Outlook.com IMAP port: 993 (SSL/TLS)
• Outlook.com credential: full address plus the account password or app password

Outlook.com and Office 365 share the same IMAP endpoint. The protocol behaviour is the same; storage limits and admin controls differ. Use the Outlook.com SMTP endpoint smtp-mail.outlook.com:587 with STARTTLS if you need to send a confirmation from the new address.

Steps#

1. Inventory the AOL mailbox

   Sign in to AOL Mail in a browser. Look at the folder list and write down approximate sizes. Empty Spam unless you have a legal reason to keep it. Empty Trash. Both folders are routinely full of decades-old junk that adds runtime without adding value. Take a screenshot of any AOL Mail filters you want to recreate as Outlook.com rules later, because Outlook.com filters are managed in a different place and the syntax does not transfer automatically.

   If you have any AOL aliases (alternate addresses for the same mailbox), note them. Outlook.com supports aliases too, but you have to set them up after the migration.

2. Generate an AOL app password

   Open login.aol.com/account/security and sign in. Enable two-step verification if it is not already on; AOL will not show the app password option without it. Click Generate and Manage App Passwords, give the entry a name like Outlook Migration, and copy the 16-character string. AOL displays the password only once.

   Revoke when finished

   The app password remains active until you delete it. Anyone who finds it can sign in to your AOL mailbox over IMAP without triggering two-step verification. Plan to revoke it the same day the migration finishes.

3. Prepare the Outlook.com mailbox

   Sign in to outlook.com with the destination account. Open Settings > Sync email and confirm IMAP is enabled (it usually is). Free Outlook.com accounts cap mail at 15 GB; if you pay for Microsoft 365 Personal or Family the cap rises to 50 GB. If your AOL mailbox is bigger than the destination limit, prune the oldest folders before you migrate or upgrade the Outlook.com side first.

   If you have two-step verification turned on for your Microsoft account, generate a Microsoft app password as well, or pick a migration tool that supports OAuth for Outlook.com. The current Microsoft direction is to require OAuth, so a tool that supports it will be more reliable over time than basic-auth IMAP.

4. Run a small dry run

   Pick a folder of 50 to 200 messages. Configure the migration tool to move only that folder. Run it. Open Outlook.com and verify:

   • Folder appears with the same name in the Outlook.com tree.
   • Message dates match AOL, not today's date.
   • Read and unread states are preserved.
   • Attachments open correctly. Test a PDF and an image.
   • Non-ASCII characters in subjects (anything with é, ü, ñ, or CJK) render correctly.

   Do not skip the dry run. Two minutes of catching a date-handling bug now saves an entire weekend of rework later.

5. Run the full migration

   Start the full sync in the evening, ideally on a Friday so the machine can run through the night without interfering with work. AOL prefers one or two parallel IMAP connections. More than that and you will see Too many simultaneous connections errors and forced disconnects.

   Disable sleep on the migration workstation. Leave it plugged in. Most tools survive a brief disconnect; what they do not survive well is a lid-close that suspends the operating system mid-FETCH. The session expires on AOL's side and the resume has to walk the whole folder again.

   A reasonable rate is 10 to 20 GB per twelve hours on a clean network. Large single folders (anything over 50,000 messages) often take a disproportionate slice of the total time because AOL throttles them harder than smaller folders.

6. Verify and cut over

   Sign in to Outlook.com. Search for known-difficult items:

   • A PDF attachment from at least five years ago.
   • A thread with accented characters in the subject.
   • A message that you remember was flagged or starred in AOL.
   • A draft, if AOL Drafts had one you cared about.

   Compare folder counts against the source. The numbers will be close but not identical because Outlook.com conversation threading collapses some messages in the count view.

   In AOL, set up forwarding to your Outlook.com address under Options > Mail Settings > General > Forwarding. Choose "Forward and keep mail in AOL" for the first 90 days so you have a fallback. Update important contacts. Change 2FA recovery addresses for the accounts that matter (banking, password manager, government services).

Gotchas to watch for#

AOL's IMAP server tends to drop sessions that have been idle for more than about ten minutes. The migration tool needs to send NOOP often enough to keep the channel alive. If you see the log full of BYE Connection closed lines followed by fresh LOGIN entries, this is what is happening. Most tools handle it transparently but the repeated reconnects extend the total runtime.

Outlook.com aggressively classifies inbound migration traffic as Junk during the first few hours. Newsletters from defunct lists, threads with broken DKIM, and anything that looks promotional often lands in Junk Email rather than Inbox. After the run, walk the Junk Email folder and move false positives to Inbox. The next time those senders send, classification will be more accurate.

The Outlook.com Drafts folder behaves differently from AOL Drafts. AOL keeps drafts as regular IMAP messages; Outlook.com sometimes hides drafts from the IMAP view because the Outlook.com web client uses a different store for drafts. Drafts that you really care about should be moved into a custom folder in AOL before the migration so they land where you can find them.

Errors you will probably see#

• AUTHENTICATIONFAILED against AOL — wrong password. Re-generate the app password and try again.
• LOGIN failed: Basic authentication is disabled against Outlook.com — switch to OAuth, or generate a Microsoft app password.
• Too many simultaneous connections — AOL throttling. Drop concurrency to one stream.
• Folder UTF-7 conversion error — AOL folder name with mixed encoding. Rename the folder in AOL to ASCII and retry.
• BYE Connection closed — IDLE timeout. Reduce keep-alive interval.

If you are seeing repeated quota messages on the Outlook.com side, the free 15 GB limit is the most likely cause. Pause the run, check storage in Outlook.com settings, and either upgrade or prune the AOL side.

Telling people you have moved#

For personal mail, forwarding catches most things and a short note covers the rest. Two sentences: "I am moving my email to Outlook.com. From now on please send to new@outlook.com so I do not lose your messages in the forwarder." Most contacts update their address book on the next reply.

For business and account-related senders, do not rely on forwarders. Update billing addresses, 2FA recovery addresses, and account-recovery contacts manually. AOL accounts that go dormant sometimes get reclaimed, and a forwarder that disappears six months later is a security incident waiting to happen.

If you are running the same job for someone moving to Gmail instead, the AOL to Gmail walkthrough covers the same source side with a different destination. For paid Microsoft 365 tenants, the AOL to Office 365 guide is the one to follow. People migrating from Yahoo will find the Yahoo to Outlook playbook covers the same Outlook.com destination side. For a broader view of the whole exercise, the complete email migration guide puts these provider pairs in context.

When things go badly wrong#

If the migration tool crashes or the workstation reboots mid-run, most well-written tools resume from the last completed folder. The risk on resume is duplicate messages, not missing ones. Search Outlook.com by sender plus subject if you suspect duplicates; Outlook.com bulk-delete handles tens of thousands of matches efficiently.

If AOL throttles you so aggressively that the run is making zero progress, stop and try at a different time of day. Throttle behaviour eases overnight in US Eastern hours. A run started at 22:00 Eastern often completes by morning when the same run started at 14:00 stalls for hours.