Quick Answer
Export Yahoo Mail to MBOX in 3 ways. Use Thunderbird add-on, copied profile files or backup software.
Add-on exports one folder at a time. Copied files work after a full sync. Software suits many folders and accounts.
Check your Yahoo IMAP settings first. MBOX files drop contacts.
You want to export Yahoo Mail to MBOX so you can open your mail in Thunderbird or Apple Mail or retain an archive before you close an account. Yahoo Mail has no MBOX button. You reach an MBOX file through a mail application that connects over IMAP or with software. Below are three ways to save Yahoo mail as MBOX, Yahoo settings you need and fixes for usual errors.
What is an MBOX file?
MBOX is a plain text format that stores many messages in one file, one file per folder. When you save Yahoo mail as 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 contains mail only. It does not contain 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 save Yahoo mail as MBOX. It needs free ImportExportTools NG add-on. That add-on exports one folder per pass.
- 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 save Yahoo mail as MBOX with every message.
- Open Tools, then Add-ons and Themes, search for ImportExportTools NG and select Add to Thunderbird.
- To save Yahoo mail as MBOX, right click a Yahoo folder you want, like 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 gives 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 save Yahoo mail as MBOX by copying Thunderbird files?
Thunderbird already stores IMAP folders as MBOX files. A Mozilla Support thread explains that layout: Mail folder contains POP accounts and Local Folders and ImapMail contains IMAP accounts. MBOX files have no extension, .msf files contain no emails and .sbd folders contain 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 save Yahoo mail as MBOX.
- Ignore .msf files, since they contain 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 save Yahoo mail as MBOX with software?
Use Corbett Yahoo Backup Tool to save Yahoo mail as MBOX in one batch. 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 assists on a weak connection. Filters work before anything is saved, by date, sender, subject, message content, attachment and size and duplicates can be ignored. It works on Windows 7 to 11 and Windows Server 2008 to 2025, with no Mac version. Free demo saves 10 emails per folder.
Steps to save Yahoo mail as MBOX with software
- Install Corbett Yahoo Backup Tool on your Windows PC and open it with Run as administrator.
- Choose Yahoo and paste your app password. Software sets
imap.mail.yahoo.comon port 993 itself. - Tick Yahoo folders you want to save Yahoo mail as 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.
Which Yahoo IMAP 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 retains 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 save Yahoo mail as MBOX suits you?
To save Yahoo mail as MBOX for one folder, use Thunderbird. Use software when you have many folders, several accounts or need filters.
| Way to save Yahoo mail as MBOX | Needs | Folders | Filters | Cost |
|---|---|---|---|---|
| Thunderbird add-on to save Yahoo mail as MBOX | Thunderbird, ImportExportTools NG, app password | One per pass or with subfolders | No | Free |
| Copying Thunderbird files to save Yahoo mail as MBOX | Thunderbird, full IMAP sync | All synced folders | No | Free |
| Corbett Yahoo Backup Tool to save Yahoo mail as 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 the export?
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 contains 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 a Yahoo MBOX export 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 works with 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 in Thunderbird
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
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 new builds may differ.
MBOX file is missing contacts
MBOX contains mail only. Export Yahoo contacts from Yahoo Contacts on their own.
What to do after the export?
After you save Yahoo mail as MBOX, open one file in Thunderbird and check dates, senders and attachments on a few messages. Retain your Yahoo mailbox until you confirm counts. Yahoo empties a mailbox left unused for 12 months, according to Corbett's page so retain a second copy of your MBOX files on another drive.
Our view
Thunderbird is free and handles one folder per pass. 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 save Yahoo mail as MBOX, connect Yahoo over IMAP first, because Yahoo Mail has no MBOX button.
- ImportExportTools NG exports one Thunderbird folder as an MBOX file per pass.
- Thunderbird retains IMAP mail as MBOX files in its ImapMail folder, with no file extension.
- An MBOX file contains mail only so export contacts on their own.
- Corbett Yahoo Backup Tool can save Yahoo mail as MBOX with filters and its free demo saves 10 emails per folder.
Questions About Yahoo MBOX Export
Can Yahoo Mail export to MBOX directly?
No. Yahoo Mail has no button to save Yahoo mail as MBOX so you route mail through a mail application or software.
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.
Will exporting delete my Yahoo emails?
No. Every way here to save Yahoo mail as MBOX copies mail. Your Yahoo mailbox remains as it was.
How do I export Yahoo Mail to MBOX?
To save Yahoo mail as MBOX, add Yahoo to Thunderbird over IMAP and export a folder with ImportExportTools NG or use Corbett Yahoo Backup Tool for many folders.
What is an MBOX file?
It is a plain text file that contains many messages, one file per folder. Thunderbird and Apple Mail open it.
Does Thunderbird export all Yahoo folders at once?
Yes. Add-on gives a With Subfolders option. Otherwise you save Yahoo mail as MBOX one folder per pass.
