MSG File vs EML File – A Detailed Comparison of Two Popular Email Formats

Email files are often saved in different formats depending on the email client you use. Among the most common formats are MSG and EML. While both are designed to store email messages, they differ significantly in terms of compatibility, structure, supported applications, and overall usability.

If you have ever wondered MSG File vs EML File, this guide will help you understand what each format is, how they work, and the major differences between them. Whether you’re an Outlook user, switching to another email client, or simply organizing your email archives, knowing these differences can help you choose the right format for your needs.

What Is an MSG File?

Rather than being a universal email format, an MSG file is specifically designed for Microsoft Outlook. It stores an individual email together with its attachments, formatting, header information, timestamps, and other Outlook-related attributes, making it suitable for users working within the Microsoft ecosystem. Besides the email body, an MSG file can also include –

• Sender and recipient details
• Subject line
• Date and time information
• Attachments
• Email formatting
• Outlook-specific metadata
• Contacts, calendar items, meeting requests, and tasks (when applicable)

Since MSG is designed specifically for Outlook, it works best within the Microsoft ecosystem. Although some third-party applications can open MSG files, full compatibility is generally limited to Microsoft Outlook.

Common Uses of MSG Files

• Saving important Outlook emails individually
• Sharing specific emails with Outlook users
• Preserving Outlook metadata
• Legal and business email record keeping
• Exporting emails from Outlook

What Is an EML File?

An EML file is a standard email message format based on internet email standards. Unlike MSG, EML is supported by multiple email clients, making it one of the most widely compatible email formats. An EML file typically stores –

• Email headers
• Sender information
• Recipient information
• Subject
• Message content
• Attachments
• MIME formatting

Because it follows open email standards, EML files can be accessed by numerous desktop email applications without relying on Microsoft Outlook.

Common Email Clients That Support EML

• Microsoft Outlook (with import/open support)
• Mozilla Thunderbird
• Windows Mail
• Apple Mail
• eM Client
• Many other email applications

Its broad compatibility makes EML a popular choice for email sharing, backup, and migration.

MSG File vs EML File – Comparison Table

Feature	MSG File	EML File
Developer	Microsoft	Open Email Standard
Primary Application	Microsoft Outlook	Multiple Email Clients
Compatibility	Outlook-focused	Cross-platform
Stores Attachments	Yes	Yes
Stores Metadata	Extensive Outlook metadata	Standard email metadata
Supports Contacts & Calendar	Yes	No
Portability	Moderate	High
Best For	Outlook users	Cross-platform email access

Key Differences Between MSG and EML Files

Although both formats store email messages, they differ in several important ways.

1. Compatibility

This is the biggest difference.

MSG files are closely tied to Microsoft Outlook. If you use Outlook daily, the MSG format offers excellent integration.

EML files, however, are compatible with many email applications across Windows and macOS, making them much easier to share and access.

Winner – EML

2. File Structure

MSG uses Microsoft’s proprietary file structure, which includes Outlook-specific properties and metadata.

EML uses standard MIME formatting that follows widely accepted internet email protocols.

Because of this, EML files are generally more flexible.

3. Metadata Support

MSG files preserve a large amount of Outlook-specific information, including –

• Categories
• Flags
• Meeting requests
• Contacts
• Outlook properties

EML files preserve standard email information but may not retain Outlook-exclusive properties.

Winner – MSG

4. Portability

If you need to move emails between different operating systems or email applications, EML is much more portable.

MSG files may require Outlook or specialized software to display correctly.

Winner – EML

5. Attachments

Both formats support email attachments.

Whether an email contains PDFs, images, Word documents, or ZIP files, both MSG and EML can preserve them during normal use.

Result – Tie

6. Long-Term Accessibility

Since EML is based on open standards, it is generally considered more future-proof.

MSG depends heavily on Microsoft’s Outlook environment, which may not always be available in every workflow.

Winner – EML

Advantages of MSG Files

MSG files are an excellent choice for users who primarily work in Microsoft Outlook. Some key advantages include –

• Excellent Outlook integration
• Preserves advanced Outlook metadata
• Supports calendar items and contacts
• Ideal for Microsoft Exchange environments
• Maintains original email formatting
• Suitable for business record management

If your organization relies entirely on Microsoft Outlook, MSG remains one of the most reliable email formats.

Advantages of EML Files

EML files are preferred when compatibility and flexibility are important. Some major benefits include –

• Supported by multiple email clients
• Easy to share across platforms
• Suitable for Windows and macOS
• Stores email content and attachments
• Based on open internet standards
• Ideal for email migration and archiving

Because of its universal support, EML is often chosen for long-term email storage and cross-platform communication.

Limitations of MSG Files

Although MSG files are excellent for Microsoft Outlook users, they have a few drawbacks.

1. Limited Compatibility – MSG is a Microsoft proprietary format. Most non-Outlook email clients cannot open MSG files directly without additional software or conversion.

2. Outlook Dependency – Many users need Microsoft Outlook installed to access MSG files properly. This becomes inconvenient when switching to another email application.

3. Difficult Cross-Platform Sharing – If you share MSG files with users who use Thunderbird, Apple Mail, or other email clients, they may not be able to open the files without converting them first.

4. Not Ideal for Email Migration – When migrating emails to another platform, many services prefer EML because it is supported by a wider range of applications.

Limitations of EML Files

Although EML is highly compatible, it also has some limitations.

1. Limited Outlook-Specific Information – EML files store standard email data but generally do not preserve certain Outlook-specific properties, such as categories, voting buttons, or other advanced Outlook attributes.

2. Calendar and Contact Support – Unlike MSG files, EML files are designed for email messages only. They are not intended to store Outlook calendar events, contacts, tasks, or meeting requests.

3. Formatting Differences – Some email clients may display fonts, embedded images, or HTML formatting slightly differently, depending on how they interpret the EML file.

Which Format Should You Choose?

There is no single “best” format for everyone. The right choice depends on how you use your emails.

Choose MSG If You –

• Primarily use Microsoft Outlook
• Need to preserve Outlook-specific properties
• Work in Microsoft Exchange environments
• Store calendar items and meeting invitations
• Require complete Outlook metadata

Choose EML If You –

• Use multiple email clients
• Need better compatibility across platforms
• Want to archive emails in a widely supported format
• Frequently switch emails from one email application to another.
• Plan to migrate emails between different applications

When Should You Convert MSG to EML?

Converting MSG files to EML can be helpful in several situations.

• Switching from Outlook to Thunderbird – Thunderbird supports EML files, making the transition easier.
• Moving to Apple Mail – Mac users often prefer EML because Apple Mail can work with this format more conveniently than MSG.
• Cross-Platform Email Sharing – If recipients don’t use Microsoft Outlook, EML files provide greater accessibility.
• Email Backup – Many users convert Outlook emails into EML format for easier backup and long-term storage.
• Email Migration Projects – Several email clients and migration workflows accept EML files, making them a practical choice during migration.

Challenges of Manual Conversion

While there are manual ways to save Outlook emails in different formats, they often become impractical when dealing with a large number of MSG files. Common challenges include –

• One-by-one conversion
• Time-consuming process
• Risk of missing attachments
• Manual file management
• Difficulty handling thousands of emails
• Limited flexibility for bulk operations

For organizations or users managing extensive email collections, manual methods may not be efficient.

An Easier Way to Convert MSG Files

If you need to convert multiple MSG files while preserving important email information, using a dedicated conversion tool can simplify the process.

MacMister MSG Converter for Mac & Windows is designed to help users convert MSG files into various formats while maintaining email properties, attachments, folder structure, and metadata. Some of its key capabilities include –

• Batch conversion of multiple MSG files
• Preserve attachments and embedded content
• Maintain email headers and metadata
• Export MSG to PDF, EML, PST, MBOX, HTML, CSV, and other formats
• Designed to operate efficiently across Windows and macOS platforms.
• Simple and user-friendly interface
• Selective conversion options for better control

This makes it a practical option for users who need to migrate or archive Outlook emails without spending hours converting files manually.

Frequently Asked Questions

Is MSG better than EML?
Neither format is universally better. MSG is ideal for Microsoft Outlook users, while EML offers broader compatibility with different email applications.

Can Outlook open EML files?
Yes. Microsoft Outlook can open EML files, although the experience may vary depending on the Outlook version and system configuration.

Which format is more compatible?
EML is generally considered more compatible because it is supported by multiple email clients across different operating systems.

Do both formats support attachments?
Yes. Both MSG and EML files can store email attachments along with the message content.

Is EML suitable for long-term email storage?
Because it follows open email standards and works with many email clients, EML is often preferred for long-term accessibility.

How can I convert MSG files without losing email information?
A professional conversion solution such as MacMister MSG Converter for Mac & Windows can help convert MSG files while preserving attachments, formatting, and essential metadata.

Final Thoughts

Both MSG and EML are reliable email file formats, but each serves a different purpose. MSG is the preferred choice for Microsoft Outlook users who need to retain Outlook-specific features and metadata. On the other hand, EML offers greater flexibility, making it suitable for users who work across multiple email clients or require better cross-platform compatibility.

If your goal is to migrate Outlook emails, share messages with non-Outlook users, or create a more portable email archive, converting MSG files to EML can be a practical solution. For bulk conversions and better data preservation, MacMister MSG Converter for Mac & Windows provides an efficient way to convert MSG files to EML and several other popular formats while maintaining the integrity of your email data.