Quick answer
- One folder at a time: add Yahoo to Thunderbird over IMAP, then use free ImportExportTools NG add-on to export a folder as an MBOX file.
- Free copy of raw files: after Thunderbird syncs, copy your folder's MBOX files from your Thunderbird profile.
- Many folders or accounts: Corbett Yahoo Backup Tool saves Yahoo Mail as MBOX with filters.
You want to export Yahoo Mail to MBOX so you can open your mail in Thunderbird or Apple Mail, or keep an archive before you close an account. Yahoo Mail has no MBOX button. You reach an MBOX file through a mail program that connects over IMAP, or with software. Below are three ways to export Yahoo Mail to MBOX, Yahoo settings you need and fixes for usual errors.
What is an MBOX file when you export Yahoo Mail to MBOX?
MBOX is a plain text format that stores many messages in one file, one file per folder. When you export Yahoo Mail to MBOX, every Yahoo folder becomes one MBOX file. Thunderbird, Apple Mail and Evolution can open it. Attachments sit inside that file as encoded text, so they travel with every message.
MBOX holds mail only. It does not hold your Yahoo contacts or calendar. For a spreadsheet of messages, see how to export Yahoo emails to CSV. For an Outlook file, see how to save Yahoo emails to computer.
How to export Yahoo Mail to MBOX with Thunderbird?
Thunderbird is free, so it is a usual first try to export Yahoo Mail to MBOX. It needs free ImportExportTools NG add-on. That add-on exports one folder per run.
- Sign in to Yahoo Account Security and create an app password under External connections. Copy that code.
- In Thunderbird add your Yahoo account over IMAP and sign in with Yahoo's window or your app password.
- Wait for your Yahoo folders to finish syncing, so you export Yahoo Mail to MBOX with every message.
- Open Tools, then Add-ons and Themes, search for ImportExportTools NG and select Add to Thunderbird.
- To export Yahoo Mail to MBOX, right click a Yahoo folder you want, such as Inbox.
- Select ImportExportTools NG, then Folder Export (mbox), then As mbox File.
- Choose a save location outside folders Thunderbird manages.
Menu names above follow a published ImportExportTools NG guide, and labels vary by Thunderbird version, so test one small folder first. That menu offers With Subfolders and Single Zipped mbox File. Do not use IMAP as your only backup. A message you delete in Thunderbird is deleted on Yahoo's server too.
How to export Yahoo Mail to MBOX by copying Thunderbird files?
Thunderbird already stores IMAP folders as MBOX files. A Mozilla Support thread explains that layout: Mail folder holds POP accounts and Local Folders, and ImapMail holds IMAP accounts. MBOX files have no extension, .msf files hold no emails and .sbd folders hold subfolders.
- Add Yahoo to Thunderbird over IMAP and let every folder finish syncing. Open every large folder once so Thunderbird downloads full messages.
- Close Thunderbird, then open your profile folder from its Help menu.
- Open ImapMail folder and then your Yahoo account folder.
- Copy files with no extension and any .sbd folders to a safe place to export Yahoo Mail to MBOX.
- Ignore .msf files, since they hold no emails.
I have not tested every Thunderbird version. If a copied file opens empty, that folder did not download in full, so use add-on steps above. Moving mail to a new host? See how to export Namecheap email to Thunderbird.
How to export Yahoo Mail to MBOX with software?
Use Corbett Yahoo Backup Tool to export Yahoo Mail to MBOX in one run. Its page says it downloads a Yahoo Mail account to PST, MBOX, EML, MSG, PDF, HTML, CSV or TXT, with folders, attachments and dates intact. Batch mode takes several Yahoo accounts from a CSV list, and pause and resume helps on a weak connection. Filters work before anything is saved, by date, sender, subject, message content, attachment and size, and duplicates can be skipped. It runs on Windows 7 to 11 and Windows Server 2008 to 2025, with no Mac version. Free demo saves 10 emails per folder.
Steps to export Yahoo Mail to MBOX with software
- Install Corbett Yahoo Backup Tool on your Windows PC and run it as administrator.
- Choose Yahoo and paste your app password. Software sets
imap.mail.yahoo.comon port 993 itself. - Tick Yahoo folders you want to export Yahoo Mail to MBOX from. Every folder and subfolder has its own checkbox.
- Preview a few messages, then add date, sender or subject filters if you need less mail.
- Choose MBOX as output format and select a destination folder.
- Start your export to save Yahoo Mail to MBOX, then open one MBOX file in Thunderbird to check it.
Licence is lifetime from $99 with a 30-day money-back window. To send Yahoo mail into another account instead of a file, use Corbett Yahoo Mail Migration Tool or see how to transfer emails from Yahoo to another account. Need only a sender list? See how to extract email addresses from Yahoo.
What Yahoo settings do you need?
Yahoo's page says an app password is needed for Yahoo Account Key or some older apps. Corbett's Yahoo page says that with two step verification on, a normal Yahoo password is rejected by every mail client. It also says Yahoo keeps an IMAP switch under Settings, More Settings, then Mailboxes, so confirm IMAP access is on. Delete your app password when you finish, since changing your Yahoo password does not cancel it.
- Incoming IMAP server:
export.imap.mail.yahoo.com, port 993, SSL required. - Username: your full Yahoo address.
- Password: an app password if Yahoo rejects your account password.
Which way to export Yahoo Mail to MBOX is best?
To export Yahoo Mail to MBOX for one folder, use Thunderbird. Use software when you have many folders, several accounts or need filters.
| Way to export Yahoo Mail to MBOX | Needs | Folders | Filters | Cost |
|---|---|---|---|---|
| Thunderbird add-on to export Yahoo Mail to MBOX | Thunderbird, ImportExportTools NG, app password | One per run, or with subfolders | No | Free |
| Copying Thunderbird files to export Yahoo Mail to MBOX | Thunderbird, full IMAP sync | All synced folders | No | Free |
| Corbett Yahoo Backup Tool to export Yahoo Mail to MBOX | Windows PC, app password | Ticked folders and subfolders | Date, sender, subject, content, attachment, size | Free demo, then from $99 |
Want other formats? See how to save Yahoo email as PDF or download all attachments in Yahoo Mail.
How to open your MBOX file after you export Yahoo Mail to MBOX?
In Thunderbird, create a folder under Local Folders, right click it and use ImportExportTools NG to import your MBOX file. On a Mac, Apple's help says to open Mail, choose File, then Import Mailboxes, select Files in mbox format and choose a folder that holds your files. Mail puts messages in a new mailbox named Import. Want your Yahoo mail in Gmail or Outlook instead? See how to import MBOX to Gmail, migrate Yahoo Mail to Gmail or migrate Yahoo emails to Outlook.
Why does export Yahoo Mail to MBOX fail?
Yahoo rejects your password in Thunderbird
A Mozilla Support user in February 2026 got "Authentication error, LOG IN invalid credentials" while adding Yahoo to Thunderbird for Android, and changing that Yahoo password did not help. A reply said Yahoo no longer supports basic sign in and suggested OAuth 2.0 or a 16 character app password, and it was marked as AI generated. That thread shows no confirmed fix. Create an app password as shown above.
Folders are empty when you export Yahoo Mail to MBOX
Wait for first sync to finish and confirm IMAP access is on under Yahoo Settings, More Settings, Mailboxes. For setup help in other clients, see how to download IMAP emails from server.
MBOX file opens empty after you export Yahoo Mail to MBOX
Thunderbird may not have downloaded full messages. Open that folder, let it sync, close Thunderbird and copy your file again.
Add-on menu is missing
Restart Thunderbird after you install ImportExportTools NG. Its add-on page names Thunderbird 115 ESR as latest version it lists, so very new builds may differ.
MBOX file is missing contacts
MBOX holds mail only. Export Yahoo contacts from Yahoo Contacts on their own.
What to do after you export Yahoo Mail to MBOX?
After you export Yahoo Mail to MBOX, open one file in Thunderbird and check dates, senders and attachments on a few messages. Keep your Yahoo mailbox until you confirm counts. Yahoo empties a mailbox left unused for 12 months, according to Corbett's page, so keep a second copy of your MBOX files on another drive.
Our view
Thunderbird is free and handles one folder per run. Raw profile files work only after a full sync. Use software for all folders at once, and open one MBOX in Thunderbird to check it.
Key takeaways
- To export Yahoo Mail to MBOX, connect Yahoo over IMAP first, because Yahoo Mail has no MBOX button.
- ImportExportTools NG exports one Thunderbird folder as an MBOX file per run.
- Thunderbird keeps IMAP mail as MBOX files in its ImapMail folder, with no file extension.
- An MBOX file holds mail only, so export contacts on their own.
- Corbett Yahoo Backup Tool can export Yahoo Mail to MBOX with filters, and its free demo saves 10 emails per folder.
Questions about export Yahoo Mail to MBOX
How do I export Yahoo Mail to MBOX?
To export Yahoo Mail to MBOX, add Yahoo to Thunderbird over IMAP and export a folder with ImportExportTools NG, or use Corbett Yahoo Backup Tool for many folders.
Can Yahoo Mail export to MBOX directly?
No. Yahoo Mail has no button to export Yahoo Mail to MBOX, so you route mail through a mail program or software.
What is an MBOX file?
It is a plain text file that holds many messages, one file per folder. Thunderbird and Apple Mail open it.
Do I need a Yahoo app password?
Yahoo says it is needed for Account Key or some older apps. Corbett says a normal password is rejected when two step verification is on.
What are Yahoo IMAP settings?
Incoming is export.imap.mail.yahoo.com on port 993 with SSL, with your full Yahoo address as username.
Does Thunderbird export all Yahoo folders at once?
Yes. Add-on offers a With Subfolders option. Otherwise you export Yahoo Mail to MBOX one folder per run.
Where does Thunderbird store IMAP mail?
In ImapMail folder of your profile. Mbox files have no extension and .msf files hold no emails.
How do I open an MBOX file on a Mac?
In Mail, choose File, Import Mailboxes, then Files in mbox format and select a folder with your files.
Which formats can Corbett Yahoo Backup Tool save?
It can export Yahoo Mail to MBOX and also PST, EML, MSG, PDF, HTML, CSV and TXT. It runs on Windows and has no Mac version.
Will exporting delete my Yahoo emails?
No. Every way here to export Yahoo Mail to MBOX copies mail. Your Yahoo mailbox stays as it was.
