Migrate Bat Emails to Gmail

Gmail has no button to migrate Bat emails. Bat keeps mail in TBB database files, and Gmail accepts no MBOX upload. Google also ended POP fetching in January 2026, so mail now has to travel over IMAP. Below are three ways to migrate Bat emails to Gmail, with real user problems, settings and limits.

Why can you not migrate Bat emails to Gmail directly?

Gmail pulls mail from servers, not from files on your PC. Bat stores every folder in a TBB file, and Gmail cannot open that format, so you cannot migrate Bat emails by upload alone. Google also removed Check mail from other accounts, so Gmail no longer pulls mail from a POP server, as The Register reported in January 2026.

That leaves one path. Turn your Bat mail into MBOX files, then upload those files to Gmail through IMAP. Forwarding Bat emails one by one does not work for old mail, because forwarded copies carry today's date. Adam Caudill, a Bat user who moved to Gmail in 2007, wrote that Gmail Loader stripped message timestamps and that his move took almost a full day.

How to export Bat emails to MBOX before you migrate?

Open Bat, select a folder, then export its messages to a UNIX mailbox file. Bat exports one folder per file, so you migrate Bat emails folder by folder.

1. Start Bat and select a folder in your folder tree, such as Inbox.
2. Open Tools, then select Export Messages.
3. Choose UNIX Mailbox as file type.
4. Name your file, for example inbox.mbox, and select Save.
5. Repeat for Sent, Drafts and every custom folder.

Menu names differ between Bat versions, so check them on screen. Keep Bat installed until your move ends. A user on thunderbird-mail.de asked in 2011 how to open a MESSAGES.TBB file, and a helper warned that import fails without Bat on your PC. Name every MBOX file after its folder so you can match counts later.

How to migrate Bat emails to Gmail with Thunderbird?

Import your exported Bat emails into Thunderbird local folders, then copy those folders into a Gmail account that you added over IMAP. Both steps are free.

1. Open Thunderbird, go to Account Settings, then use Account Actions to choose Add Mail Account.
2. Type your Gmail address and sign in through Google when a window opens. Wait while Gmail folders sync.
3. Install ImportExportTools NG from add-ons page in Thunderbird.
4. Right-click Local Folders, open ImportExportTools NG and select Import mbox file.
5. Browse to your exported files. Every file becomes a local folder with its Bat emails.
6. Right-click a local folder and select Copy to Gmail, or drag it onto your Gmail account.
7. Open Gmail in a browser and compare Bat email counts with Bat.

A Mozilla Support answer from April 2025 confirms that local folders upload to Gmail in that way. Copy folders instead of moving them. Gmail turns a folder into a label, so a message can sit under that label and still show in All Mail. Catch: Thunderbird uploads over your own internet line, so a big folder takes hours and must stay open until it ends.

How to migrate Bat emails to Gmail over IMAP?

To migrate Bat emails over IMAP, add Gmail to Bat as an account, then copy folders between your old account and Gmail. Only Bat versions with Google sign-in can connect, because Google blocked plain password sign-in for mail programs.

1. In Bat, select Account, then New Account.
2. Enter your Gmail address and choose IMAP as protocol.
3. Set incoming server imap.gmail.com, port 993, SSL/TLS. Set outgoing server smtp.gmail.com, port 465, SSL/TLS.
4. Choose Google sign-in (OAuth) when Bat asks for authentication, then approve access in your browser.
5. Open your old account folder, select Bat emails and copy them to a Gmail folder.

We have not tested these Bat menu paths on every version, so follow labels you see on screen. If your Bat version has no Google sign-in, use Thunderbird. Gmail also needs IMAP turned on in its settings. Catch: copying between accounts works folder by folder, and Bat gives no summary of failed Bat emails.

Steps to migrate Bat emails to Gmail with software

1. Export your Bat folders to MBOX files, as shown above.
2. Install MBOX Converter on a Windows PC and select Open, Email Data Files and MBOX.
3. Add your exported files or one folder that holds them all.
4. Untick folders you do not want, such as spam or old newsletters, and preview a few messages.
5. Add date, sender or attachment filters if you want less mail.
6. Select Export, choose Gmail and enter your Gmail details when asked. With 2-step verification on, create a Google app password first.
7. Start export, then check Gmail for your Bat emails under labels.

Its page does not name Bat, so test one exported folder in free demo before you buy. Files convert on your PC, and Corbett never sees your messages. A lifetime licence starts at $99 with a 30-day money-back window. For MBOX files from other sources, see how to import MBOX to Gmail.

Which way to migrate Bat emails to Gmail is best?

Use Thunderbird for one personal mailbox, Bat IMAP when your version signs in to Google and software for many folders, filters or several Gmail accounts.

Moving from another program? See how to migrate IncrediMail emails to Gmail, transfer Mailbird emails to Gmail or import EML to Gmail.

Why does Bat email to Gmail migration fail?

Old Bat emails show today's date

Forwarding creates new messages, and Gmail stamps migrated Bat emails with forward time. Upload MBOX files over IMAP instead, which keeps original dates. Adam Caudill found in 2007 that one tool stripped timestamps while another kept them, so check dates on a few old messages before you trust a method.

Thunderbird cannot open Bat TBB files

Thunderbird opens MBOX, not TBB. Export from Bat first. A 2011 thread on thunderbird-mail.de ended with a user planning to reinstall Bat to import a MESSAGES.TBB file, which fits that rule.

Gmail does not show new folders

Open Gmail settings, then Labels, and make sure imported labels are set to show. Folders from Thunderbird arrive as labels, so look in your label list on left, not in Inbox.

Upload stops halfway

Copy one folder at a time and keep your PC awake. Compare counts after every folder and repeat a failed folder only after you remove its partial copy from Gmail, or you get duplicates. MBOX Converter skips duplicate copies.

Contacts and calendar stay behind

MBOX files hold messages only. Corbett MBOX Converter does not convert calendar entries, client settings or filter rules. Export your Bat address book on its own and import it into Google Contacts.

What to do after you migrate Bat emails to Gmail?

After you migrate Bat emails, open a few old messages with attachments in Gmail and compare folder counts with Bat. Keep a copy of your Bat emails as MBOX files on a USB disk until you are sure. Need a second copy of your new Gmail data? See how to clone a Gmail account. Want a local copy of Thunderbird mail too? See how to export Thunderbird emails.

Questions about migrating Bat emails to Gmail