A short walkthrough showing how to save your complete Outlook.com or Hotmail mailbox to an external hard drive using 4n6 Outlook.com Backup software. The tool writes the output directly to your chosen drive in PST, MBOX, EML, PDF and other formats, and preserves folders and attachments exactly as they are on the server.
Video Transcript
Hello and welcome. In this video we show how to backup your Outlook.com mailbox to an external hard drive using 4n6 Outlook.com Backup software. The same method works for any Hotmail, Live.com or MSN account because Microsoft folded all of them into Outlook.com years ago.
Plug your external drive into the PC before starting so the tool can write the backup directly to it. Install the software from the vendor website and launch it. Click Open in the menu and pick Add Account. Choose Outlook.com from the service list.
Enter your Outlook.com email address and password. If you have two-factor authentication enabled you will need an app password instead. Click Add and the tool connects to Microsoft servers using IMAP on outlook.office365.com port 993.
Your full folder tree loads: Inbox, Sent, Drafts, Junk, Archive and any custom folders. Click any email to preview content, attachments, raw headers or hex values. Use the search bar to filter by sender, subject or date range.
Click Export and choose your output format. PST is best for Outlook desktop. EML keeps messages as individual files. MBOX works for Thunderbird. PDF archives the visual rendering.
Click Browse and point the destination directly at your external drive, for example D:\Outlook-Backup or E:\Hotmail-2026. Optional filters let you limit by date range, exclude Junk and Trash, or add headers. Click Save to start.
The tool writes directly to the external drive, so your C: drive stays untouched. A 2 GB mailbox takes about 15 minutes on a 100 Mbps connection. When done, safely eject the drive. Thanks for watching and please subscribe.
Why Save Outlook.com to an External Drive
Outlook.com has generous storage (15 GB free, 50 GB with Microsoft 365), but cloud storage is not a backup. Microsoft's inactive account policy deletes mailboxes after 2 years of no sign-ins. Compromised accounts also get mass-wiped by attackers before the owner notices. Keeping a physical copy on a drive you control is the only way to be certain the data survives.
The 4n6 Outlook.com Backup tool is a Windows desktop app that connects to your mailbox via IMAP, downloads every folder, and writes the output in whatever format you pick. Because the tool can write directly to an external drive, the backup never occupies space on your internal SSD. For Yahoo, Gmail and other services we covered Yahoo Mail backup and the broader Email Backup Wizard that covers Gmail, Yahoo and Outlook in one tool.
System Requirements and Supported Accounts
| Requirement | Value |
|---|---|
| Operating system | Windows 11, 10, 8.1, 8, 7. Also Windows Server 2019, 2016, 2012 R2, 2008. |
| macOS | Not supported natively. Runs on Mac via Parallels or Boot Camp. |
| RAM | 4 GB minimum. 8 GB recommended for mailboxes above 10 GB. |
| External drive | Any drive Windows can mount: USB flash, USB HDD, USB SSD, SD card, eSATA. Drive must have free space equal to 1.2x your mailbox size. |
| Supported account types | Outlook.com, Hotmail.com, Live.com, MSN.com, Windows Live and Hotmail Plus accounts. All use the same IMAP backend. |
| Output formats | PST, MBOX, EML, MSG, EMLX, PDF, HTML, MHT, RTF, DOC, CSV, vCard. |
| Direct migration | Gmail, G Suite, Office 365, Yahoo Mail, Thunderbird, Exchange, iCloud, Zoho Mail, AOL, IMAP servers. |
| Network | Stable internet. IMAP connects to outlook.office365.com on port 993 (SSL). Firewall must allow outbound TCP. |
| Demo limit | Free version backs up a partial mailbox. Licence removes the cap. |
8 Steps to Backup Outlook.com to External Drive
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Plug your external hard drive or USB into the PC. Open File Explorer and confirm the drive is visible with a letter (usually D: or E:). Create a new folder on it like Outlook-Backup so the output has a clean landing spot.
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Download 4n6 Outlook.com Backup software from the official vendor site. Install it, then launch the application. The main interface shows Home, Open, Export and Help tabs.
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Click Open in the top menu, then choose Add Account. From the service list pick Outlook.com. The dialog also covers Hotmail, Live and MSN addresses because they use the same server.
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Enter your full email address. For the password field, paste your regular Outlook.com password. If you have two-step verification enabled, generate an app password from Microsoft Account security and use that instead.
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Click Add. The tool connects to Microsoft's IMAP server and loads your folder tree. You see Inbox, Sent, Drafts, Junk, Archive and any custom folders. Click any email to preview content, attachments, headers or raw view.
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Click Export in the menu. Pick your format. PST for Outlook desktop. EML for individual messages. MBOX for Thunderbird or Apple Mail. PDF for a frozen archival snapshot.
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Click Browse. Navigate to the folder you created on the external drive, for example D:\Outlook-Backup. Enable optional filters: Date Range, Include Attachments, Exclude Junk and Trash, Add Headers.
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Click Save. The tool writes each message directly to the external drive with a progress bar. A 2 GB mailbox takes about 15 minutes on a 100 Mbps connection. When finished, verify the files in File Explorer, then safely eject the drive.
Common Errors and Fixes
| Error or symptom | Cause and fix |
|---|---|
| "Login failed" or "Invalid credentials" | You have two-step verification on but entered your main password. Generate an app password from Microsoft Account security and paste the 16-character code without spaces. Or you typed the wrong password. Try signing into outlook.live.com in a browser to confirm it works first. |
| "Cannot connect to outlook.office365.com" | Firewall blocking port 993. Open Windows Defender Firewall, add an Allow rule for the 4n6 executable on TCP outbound. On corporate networks ask IT to whitelist *.outlook.office365.com on port 993. |
| "The destination drive is full" during export | External drive filled up mid-backup. Output PST or MBOX is incomplete and will not open. Delete the partial file, free space on the drive (or use a bigger one), and re-run the full export from scratch. |
| "Disk is write-protected" | External drive is NTFS-formatted read-only, or has the hardware write-protect switch on. Check the physical switch on USB flash drives. For NTFS read-only on macOS Boot Camp, reformat as exFAT which both Windows and Mac can write to. |
| Backup freezes at a specific email | One message has a malformed MIME header or corrupt attachment. In the software preferences, enable Skip on error and re-run. The tool logs the skipped message IDs so you can inspect them later via Outlook.com webmail directly. |
| Output PST will not open in Outlook | The PST is over Outlook's 50 GB limit or was interrupted mid-write. For large mailboxes, enable Split PST in export options so the tool produces multiple 10 GB files. For interrupted files, re-run the backup, do not try to repair with scanpst.exe because it is unreliable on partial PSTs. |
| Junk or Trash folder missing from backup | The export filter Exclude Junk and Trash is enabled by default in some versions. Open the filter panel, untick that option, re-run. If you want those folders for forensic or compliance reasons, always check the filter state before starting. |
How 4n6 Compares to Other Outlook.com Backup Tools
Outlook.com backup has several credible tools. Here are the main alternatives with what each does well.
| Tool | Strengths and trade-offs |
|---|---|
| 4n6 Outlook.com Backup (this video) | Windows only. Starts around USD 49. Free demo with partial backup. 12+ output formats, direct migration to other services, date and sender filters. Good all-rounder for personal users. |
| AOMEI Backupper Professional | Windows. Around USD 50. Has built-in scheduler for automated repeat backups. Backs up to internal, external, NAS and cloud destinations. Fewer export formats than 4n6 but better automation. |
| MailStore Home | Free for personal use. Cross-mailbox search is excellent. Imports into its own archive format which is secure but not directly portable. Good if you only need to read the archive, not import it elsewhere. |
| Thunderbird (free) | Free and open source. Add Outlook.com via IMAP, Thunderbird caches all messages in MBOX. No PST export without a separate Thunderbird to Outlook converter. Best budget option. |
| Outlook desktop + Import/Export wizard | Free if you already have Outlook. Add Outlook.com account, let it sync, then export to a PST file via File > Open and Export > Import/Export. PST only. Works but requires a licensed Outlook. |
| SafePST Backup | Dedicated PST backup tool. Polished UI, good scheduler. Only exports to PST format, no EML or MBOX. Around USD 35. Best for users who only care about PST. |
Performance Notes from Real Testing
Tested on a Dell Latitude 5420 (Intel i5-1145G7, 16 GB RAM, NVMe internal SSD) writing to a Seagate Backup Plus 2 TB external USB 3.0 HDD over a 100 Mbps home connection.
| Mailbox profile | Result |
|---|---|
| Small Outlook.com, 250 MB, 1,100 messages | Full backup in 2 minutes 20 seconds. PST output: 268 MB. Zero failed messages. External drive spin-up added 3 seconds. |
| Medium account, 2.4 GB, 18,000 messages | Full backup in 17 minutes. PST: 2.5 GB single file. Memory peaked at 780 MB. Write speed to external: ~35 MB/s sustained. |
| Large account, 12 GB, 65,000 messages with attachments | Full backup in 2 hours 10 minutes. PST split into 2 files at 10 GB each. External drive stayed cool, no thermal throttling. Memory peaked at 1.6 GB. |
| Hotmail account from 2005 with legacy messages | Full backup in 45 minutes for 4.8 GB. Some pre-2010 messages had malformed headers, tool auto-converted them. No manual intervention needed. |
| Backup to a USB 2.0 flash drive instead of USB 3.0 HDD | Same 2.4 GB mailbox took 38 minutes vs 17 minutes on USB 3.0. USB 2.0 is the bottleneck, not the tool. Use USB 3.0 drives for anything above 1 GB. |
What Happens to Your Data
The backup runs entirely on your PC. Your Outlook.com credentials go directly from the 4n6 tool to Microsoft's IMAP server over an SSL-encrypted connection (port 993). No third-party cloud or server is involved. The tool caches nothing externally; all output lands on the destination folder you chose, which in this case is the external drive. If you used an app password, you can revoke it any time from the Microsoft Account app passwords page without changing your main password. After the backup, unplug the external drive and store it somewhere separate from your computer so a single incident (theft, fire, hardware failure) does not destroy both copies.
đź’ˇ Pro tips
- Use a USB 3.0 or USB-C external drive. USB 2.0 flash drives cap out around 25 MB/s which triples the backup time for anything over 1 GB.
- Format the external drive as exFAT if you plan to use it on both Windows and Mac. NTFS is Windows-only, and FAT32 cannot hold files above 4 GB which kills large PST exports.
- Run a small test backup first with the date filter set to the last 7 days only. That validates the credentials, the drive and the format before you commit to a multi-hour full backup.
- Keep two external drives and alternate between them. If one fails, you still have last month's backup on the other.
- After completion, open one random PST or MBOX file in the matching email client to verify the backup actually works. An output file that exists on disk but cannot be read is worse than no backup at all.
Frequently Asked Questions
Does this work with Hotmail, Live.com and MSN accounts?
Yes. Microsoft merged Hotmail, Live.com, MSN and Outlook.com into a single backend called Outlook.com. All of them use the same IMAP server (outlook.office365.com on port 993), so the same backup tool and the same steps work for every one of those address types.
What file format should I pick for the external drive backup?
Pick PST if you ever plan to import the backup into Outlook desktop. PST is a single-file archive and preserves folders, attachments and metadata exactly. Pick MBOX if you prefer Thunderbird or Apple Mail. Pick EML if you want individual message files that open in almost any client. Avoid PDF unless archival reading is your only goal because PDF cannot be re-imported into an email client.
Do I need to keep the external drive connected during the whole backup?
Yes. The tool writes the output file directly to the external drive as it processes emails. Unplugging the drive mid-backup will produce a corrupt PST or incomplete MBOX file. For large mailboxes above 10 GB, use a drive with its own power supply rather than a bus-powered USB drive that relies on the PC port.
Will I need an app password if I use two-step verification?
Yes. Microsoft blocks regular passwords from IMAP access when two-step verification is enabled on the account. Generate an app password from Microsoft Account security and paste it into the software in place of your normal password. The tool then authenticates as if it were a standalone mail client.
How much space do I need on the external drive?
Allow 1.2 times the size of your Outlook.com mailbox. A 5 GB mailbox typically needs about 6 GB of free space on the drive because of format overhead and attachment decoding. Check your current mailbox size in Outlook.com by going to Settings > General > Storage. If you export to PDF the output can be up to 3 times larger than the original mailbox.
Can I schedule the backup to run automatically later?
The 4n6 Outlook.com tool does not have a built-in scheduler. For repeated backups you have to start the job manually. If you need scheduled automated backups, look at AOMEI Backupper or MailStore Home, both of which offer task scheduling at the cost of fewer export formats. You can also run the 4n6 tool on demand once a month and rotate between two drives for redundancy.