addr

.addrAddress Book File

Various (Email Clients, Contact Managers) · 1990s

Developer
Various (Email Clients, Contact Managers)
Category
Database
MIME Type
application/x-addressbook
First Released
1990s
Open Format
Yes
File Signature
N/A (format varies by application)
At a Glance
.addr
Address Book File

An .addr file is a contact list or address book used by various applications to store names, addresses, and other contact details.

Reviewed on June 3, 2026
Compression
Varies (Often Plain text or Binary)
Transparency
No
Editability
Medium
Best for
Contact storage

Key Features

  • Stores contact details like names, emails, and phone numbers.
  • Primarily used by email clients and contact management software.
  • Can be plain text or a proprietary binary format.
  • Facilitates easy access to contact information within specific applications.

Best For

  • Simple storage of contact details for specific applications.
  • Quickly accessing recipient information within a compatible email client.
  • Basic contact list management.

Less Ideal For

  • Interoperability with a wide range of applications (use vCard/VCF instead).
  • Storing large amounts of complex data beyond basic contact info.
  • Sharing contacts across different operating systems or platforms without conversion.
  • Archiving or backing up sensitive contact data.

Common Use Cases

  • Storing your personal or professional contact list.
  • Exporting contacts from one application to import into another (if compatible).
  • Maintaining a directory of recipients for email correspondence.
  • Organizing client or customer information.

How to Open It

  1. Attempt to open the .addr file with the email client or contact manager that created it.
  2. Look for import/export options within your preferred contact application, specifically for address book files.
  3. If the file is plain text, try opening it with a text editor like Notepad (Windows) or TextEdit (macOS) to view its contents.

What is a .addr file?

An .addr file is typically used to store contact information, such as names, addresses, phone numbers, and email addresses. These files are commonly generated and used by email clients and contact management applications. While not a universal standard like a vCard, they serve as a straightforward way for specific software to maintain user address books. Opening an .addr file usually requires the application that created it or a compatible contact management tool.

Programs That Open .addr Files

PlatformProgram
WindowsMicrosoft OutlookPaidOfficial
Windows Live MailFreeOfficial
macOSApple ContactsFreeOfficial
LinuxThunderbirdFree

How to Convert .addr Files

FormatMethod
.VCFExport from application, Online converters

Common Problems with .addr Files

⚠️ Cannot open .addr file on a new computer or with different software.
Try exporting contacts from the original application as a VCF (vCard) file, which is more universally compatible, or find software that specifically supports .addr import.
⚠️ .addr file contents are unreadable or appear as garbled text.
The file may be in a proprietary binary format. Attempt to open it with the original application or use a specialized tool if available. If it's text, ensure you're using a plain text editor.

Frequently Asked Questions

What is the difference between an .addr file and a .vcf file?

.vcf (vCard) is a widely recognized standard for contact information, ensuring compatibility across many applications and platforms. .addr files are often proprietary to specific applications, making them less portable.

Can I convert an .addr file to a format like CSV?

Yes, if you can open the .addr file in an application that supports exporting to CSV, or if you can convert it to an intermediate format like VCF and then to CSV.

Is an .addr file safe to open?

Generally, yes, if it comes from a trusted source and you are opening it with your intended contact management software. However, as with any file, be cautious of unknown sources.

Technical Details

The structure of .addr files can vary significantly between different applications, as it's not a strictly defined open standard. They often contain plain text or a simple binary format to store fields like 'Name', 'Email', 'Phone', and 'Address'. Some applications might use proprietary formats for these files.

Did You Know?

Many older email clients utilized .addr files as their primary address book format.
The 'addr' extension is generic enough that other, unrelated applications might also use it.

Security Information

Address book files can contain sensitive personal information. Exercise caution when sharing or transferring .addr files, especially from unknown sources. Ensure you are using reputable software to open and manage these files to avoid potential malware or data corruption.

Related Extensions