Outlook IAF File Explained: Contents, Security, and Migration
Microsoft Outlook is everywhere. People use it for years, and then one day they need to move: new PC, new mail hosting, or a new mailbox policy. Suddenly, you face the same tedious problem: account configuration.
Why click through 20 dialog boxes and risk making a typo, when the configuration can be a single file?
That file is often an IAF.
An IAF (Internet Account File) is an Outlook configuration file designed for "internet mail" accounts. It creates a container for standard email protocols like POP3 and IMAP (for incoming mail) and SMTP (for outgoing mail). You can import it to fill settings instantly, or read it to understand exactly what a working setup contains.
But don't be fooled by the "just settings" feeling. An IAF file can carry enough details to fully recreate a mailbox connection, making it a sensitive asset.
What is inside an Outlook IAF file?
An IAF acts as a blueprint for an email account. In real-world scenarios, it usually includes:
- Server and Protocol Settings: Hostnames, specific port numbers (like 993 for IMAP or 587 for SMTP), and security choices. This is the part users most frequently type wrong.
- Identity Data: The email address, display name, account label, and often the login/username.
- Authentication Configuration: This is the risky part. Sometimes it contains simple flags like "remember password." Other times, it holds opaque data tied to stored credentials.
- Encryption Standards: It defines whether the connection uses SSL/TLS encryption to protect data in transit.
While you may not see the password as plain text immediately, you cannot assume it is harmless. If an IAF ends up in a support ticket, a chat log, or a forwarded email thread, it can quietly become a security vulnerability.
The Simple Rule: Treat it as a Secret
Treat an IAF like a credential until you have inspected it.
If you must share it, never treat it like a harmless screenshot. Keep access limited, use time‑limited links, and ensure the file doesn't live forever in random public folders.
Why this matters for Email Migration
If you are a hosting company or an IT support professional, the IAF is a practical tool. You can provide a ready-to-import configuration file, allowing users to finish setup with just a few clicks rather than wasting time in Outlook's manual setup screens.
If you are handling a migration yourself, an old IAF can serve as a reference point. It reveals exactly what the old account was doing, allowing you to reproduce the environment correctly.
Automating Outlook Configuration with PHP
For developers looking to automate this process-such as building web forms for import/export-you need a way to programmatically handle these files.
I have prepared instructions IAF Decoder/Coder PHP class for Outlook that allows you to parse and generate these configuration files directly within your application.
