Attaching an email as a separate file within another message is a crucial skill for professional communication. Unlike a standard forward, which merges the text into your current thread, attaching an email preserves the original message's integrity, including its metadata, internet headers, and formatting. This practice is standard in legal, technical support, and project management environments where an audit trail is necessary.

Quick Summary of Methods

For those looking for an immediate answer, here are the primary ways to attach an email based on your version of Outlook:

  • Classic Desktop (Windows): Right-click the email in your list and select Forward as Attachment, or use the shortcut Ctrl + Alt + F.
  • New Outlook & Web: Open a new message, then drag the desired email from your inbox list directly into the body of the new message. Alternatively, click the three dots (...) menu and choose Forward as attachment.
  • Multiple Emails: In the desktop version, go to Insert > Outlook Item to select several emails at once from any folder.

Understanding Why You Should Attach Instead of Forwarding

While "Forwarding" is the most common way to share information, it has significant technical limitations that "Attaching" overcomes. Understanding these nuances is essential for maintaining professional data standards.

Preservation of Internet Headers

When you forward an email, Outlook strips away the technical "header" information—the data that shows the exact path the email took across servers, security verification (SPF/DKIM), and the original timestamp. For IT security teams investigating phishing or for legal teams verifying the origin of a document, these headers are vital. Attaching the email as a .msg or .eml file keeps these headers intact.

Maintaining Original Formatting and Attachments

Forwarding often breaks the layout of complex HTML emails. It also requires you to manually ensure that any attachments in the original email are included in the forward. By attaching the email as a file, the recipient receives a perfect carbon copy. When they open the attachment, it appears exactly as it did in your inbox, complete with its own original attachments and signature layouts.

Organizational Efficiency

If you need to send five related emails to a manager, forwarding them individually creates five separate threads in their inbox, leading to clutter. Attaching all five messages to a single "summary" email allows the recipient to stay organized, keeping all related context in one place without flooding their notification tray.

Attaching Emails in the Classic Outlook Desktop App

The classic version of Microsoft Outlook (part of Microsoft 365 or Office 2021/2019) remains the powerhouse for most corporate users. It offers the most robust set of tools for item attachment.

The Drag-and-Drop Method (Most Intuitive)

In our testing, the drag-and-drop method is the most efficient workflow for users with large monitors or dual-screen setups.

  1. Open Outlook and click New Email to start your draft.
  2. Adjust the windows so you can see both your Inbox list and the New Message window simultaneously.
  3. In your Inbox, click and hold the email you wish to attach.
  4. Drag it over to the body of the new message.
  5. Release the mouse button. The email will instantly appear in the "Attached" field, usually as a .msg file.

Pro Tip: You can select multiple emails by holding the Ctrl key while clicking, then drag the entire group into your draft at once.

The "Forward as Attachment" Keyboard Shortcut

For power users who prefer keyboard productivity, Outlook includes a specific command that bypasses several menu clicks.

  1. Highlight the email in your message list.
  2. Press Ctrl + Alt + F on your keyboard.
  3. A new message window will automatically open with the selected email already attached.
  4. This method is significantly faster than right-clicking, especially when you are processing dozens of emails in a session.

Using the "Outlook Item" Tool (The Precise Way)

If you are already deep into writing a long email and realize you need to attach a message located in a different folder (like "Sent Items" or a custom "Project X" folder), use the Insert tool.

  1. In your message draft, navigate to the Insert tab on the top ribbon.
  2. Click Outlook Item.
  3. A dialog box will appear showing your entire folder structure.
  4. Navigate to the specific folder, select the email(s), and ensure that under "Insert as," the Attachment option is selected.
  5. Click OK.

This method is superior when you don't want to leave your current window or hunt through different folders in your main view.

Navigating the New Outlook and Outlook Web Experience

Microsoft's "New Outlook" for Windows and the web-based Outlook.com/OWA have a streamlined interface. While some classic features are hidden, the attachment functionality is still highly accessible.

The Modern Drag-and-Drop

In the web and "New" versions, dragging and dropping is the primary intended method. However, since these often run in a single browser tab or window, the interaction is slightly different.

  1. Start a New Mail or hit Reply.
  2. In the message list (the middle pane), find the email you want to attach.
  3. Click and drag the email. You will see a small icon follow your cursor that says "Drop messages here."
  4. Drop it into the composition pane on the right.
  5. The message will be converted into an .eml attachment.

The More Options Menu

If you prefer menu-based navigation or are working on a smaller screen where dragging is difficult:

  1. Select the email in your inbox list (do not open it, just highlight it).
  2. Click the three dots (...) or the More icon in the top toolbar or the message header.
  3. Select Other reply actions (if in a reply) or simply look for Forward as attachment.
  4. A new draft will emerge with the file attached.

Note: In the New Outlook, attachments are typically saved in the .eml format, which is more universally compatible with non-Microsoft email clients like Gmail or Apple Mail.

How to Attach Emails in Outlook for Mac

Outlook for Mac (both the Legacy and New versions) follows the macOS design language, which emphasizes drag-and-drop functionality over deep ribbon menus.

  1. Open your Outlook for Mac client.
  2. Select New Message or Reply.
  3. Simply drag the email from your list and drop it into the body of the new message.
  4. On Mac, this action usually creates a .eml file.

If you are using the Legacy Outlook for Mac, you can also use the top menu bar: Select the email, go to Message > Forward as Attachment. In the New Outlook for Mac, this option is found under the ... (More) menu in the message header.

Solutions for Outlook on Mobile Devices (iOS and Android)

A common frustration among mobile users is the lack of a "Forward as Attachment" button in the Outlook app for iOS and Android. Currently, the mobile app focuses on simple forwarding. However, there are two professional workarounds if you must send an email as an attachment while on the go.

The "Print to PDF" Workaround

This is the most reliable way to share a fixed version of an email from your phone.

  1. Open the email in the Outlook mobile app.
  2. Tap the three dots (...) in the top right corner of the message.
  3. Select Print.
  4. On the print preview screen, use the "Share" icon (iOS) or "Save as PDF" (Android).
  5. Save the PDF to your device.
  6. Create a new email and attach the PDF file you just created.

While this doesn't preserve the .msg format, it provides a perfect visual record of the communication.

The Browser Workaround

If you absolutely need the message in a proper email format (like .eml), you must bypass the app.

  1. Open your mobile browser (Chrome or Safari).
  2. Go to outlook.office.com or outlook.com.
  3. In your browser settings, select Request Desktop Site.
  4. Log in and follow the steps for "Outlook Web" described above. This allows you to use the "Forward as attachment" menu option that is missing from the app.

Technical Differences Between .msg and .eml Attachments

When you attach an email, Outlook chooses a file format based on the version you are using. Knowing the difference is helpful for ensuring your recipient can actually open what you send.

Feature .msg (Outlook Message Format) .eml (Electronic Mail Format)
Primary Creator Classic Outlook for Windows New Outlook, Web, Mac, Gmail
Compatibility Best for other Outlook Windows users Universal (works on almost all clients)
Content Includes all properties, MAPI data Plain text and MIME headers
Use Case Internal corporate environments Sending to external or non-Outlook users

In our experience, if you are sending an attachment to someone using a Mac or a mobile device, the .eml format (generated by New Outlook or the Web version) is much less likely to cause "Winmail.dat" errors or attachment corruption.

Troubleshooting Common Issues with Outlook Attachments

Even with the right steps, you might encounter roadblocks. Here is how to resolve the most common issues.

Why is the "Insert Outlook Item" Button Greyed Out?

This usually happens if you are trying to attach an item while the cursor is not in the body of the email. Click inside the white space where you type your message, and the ribbon options should light up. Additionally, if you are using a "Plain Text" format for your emails, some attachment features may behave differently. Switch to HTML formatting via the Options tab.

The Drag-and-Drop Feature Isn't Working

If you find that dragging an email doesn't do anything, it might be due to a frozen Outlook process or an administrative restriction. A quick fix we often recommend is to restart Outlook in "Safe Mode" (hold the Ctrl key while launching the app) to see if an add-in is interfering with the drag-and-drop handler.

Dealing with Large Email Attachments

If the email you are attaching contains large files (like 4K videos or high-res CAD drawings), you may exceed the attachment size limit (usually 20MB to 33MB depending on your organization). In this case, don't attach the email directly. Instead:

  1. Save the original email's attachments to OneDrive or SharePoint.
  2. Link to those files in your new message.
  3. Then, forward the original email as a standard forward to provide the text context.

Maximizing Productivity with Outlook Attachment Shortcuts

To truly master Outlook, you should integrate these habits into your daily workflow.

  • Batch Archiving: If you are closing a project, select all relevant emails in your inbox, use Ctrl + Alt + F, and send them to your project's archive address or a lead manager.
  • The "Drafts" Trick: If you aren't ready to send the attachment yet, drag the email into a draft and close it. Outlook will save that draft with the email attachment intact, allowing you to return to it later from any device.
  • Custom Quick Steps: In Classic Outlook, you can create a "Quick Step" that automatically forwards messages as attachments to a specific person (like an assistant or a CRM system) with just one click from the Home tab.

Frequently Asked Questions

Can I attach a meeting invitation to an email?

Yes. In the Classic Desktop version, use the Insert > Outlook Item method and select your Calendar folder instead of your Inbox. You can then select a specific meeting or appointment to attach as a .ics or .msg file.

Is it possible to attach an email from a different account?

If you have multiple accounts configured in Outlook (e.g., a work account and a personal account), you can drag an email from your Work Inbox into a New Message window opened under your Personal account. Outlook handles the cross-account transfer automatically.

Can I open an attached email on my phone?

Most modern mobile email apps (Outlook for iOS/Android, Apple Mail, and Gmail) can open .eml files. However, .msg files created by Classic Outlook can be difficult to open on mobile devices without a third-party "MSG Viewer" app.

How do I attach an email using the "Attach File" button?

While the "Attach File" button is usually for documents (PDFs, Word), in Classic Outlook, you can click Attach File > Browse This PC, but this will only let you select files saved on your hard drive. To attach an internal Outlook message, you must use the Outlook Item button or the drag-and-drop methods mentioned above.

Does attaching an email include its original attachments?

Yes. When you attach an email as a file, it acts as a container. When the recipient opens that container, every file that was attached to the original message remains accessible inside it.

Summary

Attaching an email in Outlook is a fundamental task that ensures your professional communication is clear, organized, and technically sound. Whether you use the classic Ctrl + Alt + F shortcut in the desktop app, the modern drag-and-drop interface in the web version, or the Print-to-PDF workaround on mobile, you now have the tools to handle any scenario.

By choosing to attach instead of simply forwarding, you preserve vital headers and formatting, making life easier for your recipients and maintaining a higher standard of data integrity. Experiment with these methods to find the one that best fits your specific version of Outlook and your daily workflow.