What is the RWZ file format?
.rwz is a settings file associated with Microsoft Outlook, used to export and import the Rules Wizard rule set. .rwz files store email rules that can be transferred between Outlook installations, making them useful for backup or cross-machine migration. Up to Outlook 2000, rules were kept in a standalone .rwz file on the local machine; from Outlook 2002 onward, Outlook shifted to storing rules as a hidden message inside the .pst mailbox data file, though classic desktop Outlook continued to support exporting and importing rules to and from .rwz for compatibility.
Processing large quantities of email messages always comes with the risk of omitting some important elements. Therefore many email clients allow users to create custom filter rules for automated and periodic email message processing. Custom rules stored in .rwz files determine how messages should be parsed and processed - covering conditions such as sender address or subject keywords, actions such as moving or deleting a message, and exceptions. Email rules can be used to effectively organize messages and filter spam.
The .rwz format is a proprietary closed binary produced by Microsoft; it carries no email content, only rule definitions. The newer Outlook for Windows and Outlook on the web store rules server-side and no longer read or produce .rwz files, so the format belongs squarely to classic desktop Outlook on Windows. For raw inspection, a hex editor can open the file; the community project OutlookRulesReader has reverse-engineered the internal record layout.
Security & safety
RISK: LOWAn .rwz contains only rule definitions, not executable code or email content, so the file itself is low-risk. The realistic caution is functional: imported rules with a forward or auto-reply action could redirect your mail, and rules can reference accounts/folders that don't exist on the new profile and silently misbehave - review your rules after importing. Only import .rwz files you created or trust, since a malicious rule set could, for example, auto-forward incoming mail.
Format details
in a nutshellPrograms that open RWZ files
Windows2 apps
Microsoft Outlook (classic desktop)
Paid File - Manage Rules & Alerts (or Rules - Manage Rules & Alerts) - Options - Import Rules, then pick the .rwz. The only program that actually applies the rules.
7-Zip / hex editor (inspection only)
Open-source Open in a hex editor to glimpse rule names as text - it's a closed binary, so this is for curiosity, not editing. Use Outlook to actually use the rules. Technical details
deep spec| Developer | Microsoft Corporation |
| Format type | Proprietary closed binary; produced exclusively by classic desktop Outlook |
| Byte order | Little-endian |
| Data encoding | Binary (no text or XML representation) |
| Internal structure | Sequential binary records, one per rule, encoding name, conditions, actions and exceptions as MAPI-style property values |
| MIME type | application/octet-stream |
| Typical file size | 1 KB - 200 KB depending on number and complexity of rules |
| Associated platform | Windows only; no macOS or mobile support |
| Primary use | Export and import of Outlook Rules Wizard rule sets for backup or cross-machine migration |
| Rule storage evolution | Up to Outlook 2000: standalone .rwz file on disk; from Outlook 2002+: rules stored as a hidden message inside the PST/OST mailbox |
| Internal format version | Undocumented; record layout varies slightly across Outlook 2000, 2002, 2003 and 2007+ exports |
| File identification | No published magic-byte signature; identified by .rwz extension and Outlook Rules and Alerts export origin |
| Carries email content | No - stores rule definitions only (conditions, actions, exceptions); contains no message data |
| Superseded by | Server-side and in-mailbox rule storage; new Outlook for Windows and Outlook on the web do not export .rwz |
| Community documentation | hughbe/OutlookRulesReader (GitHub) reverse-engineers the internal binary record layout |
| Released | 1997 (Outlook 97 / 98 Rules Wizard) |
| Latest version | N/A (no public version scheme; format last produced by classic desktop Outlook export) |
| Specification | github.com |
RWZ conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about RWZ files.
