What are the steps to attach an email to another email in Outlook

TL;DR: Most guides show you one method for attaching an email in Outlook and assume that covers it. This one walks IT company owners through all four practical approaches, including bulk attaching, PDF export, and working around file size limits, so you leave with the right method for your specific situation, not just the easiest one.

What it means to attach an email in Outlook

Most people use "attach an email" to mean three different things, and picking the wrong method wastes time.

Forwarding sends the original email as a new message with its content visible in the body. Attaching as a file embeds the original as a .msg or .eml file that the recipient opens separately, keeping your compose window clean. Copying inline pastes the text directly into your draft, no file involved.

Knowing which one you need before you start is the whole game. If you're escalating a client thread to your manager, attaching as a file keeps the chain intact and auditable. If you just need someone to see a quote, forwarding is faster.

This article focuses on how to attach an email as an attachment in Outlook, covering all four methods: drag-and-drop, Insert menu, Forward as Attachment, and the right-click option. For a broader look at what attaching mail in Outlook actually means, that post covers the concept in full.

How to attach an email to another email in Outlook: 4 steps

Drag-and-drop is the fastest way to attach email to another email in Outlook when you want to embed a full message, headers and all, inside a new compose window. It works in Outlook for Windows (Microsoft 365 and standalone 2019/2021) and takes under two minutes once you know the sequence.

Before you start, make sure you understand what attaching mail in Outlook actually means versus forwarding or copying text, since the method changes depending on your goal.

Step 1: Open a new compose window: Click "New Email" in the Home tab. Keep this window open and visible on screen. You'll need to see both the compose window and your message list at the same time, so resize or snap the windows side by side if needed.

Step 2: Find the email you want to attach: In your inbox or any folder, locate the message. Do not open it. You're working from the message list, not the reading pane.

Step 3: Drag the message into the compose window: Click and hold the email in the message list, then drag it directly into the body of the new message. Release it there. Outlook converts it into a .msg attachment automatically. You'll see it appear as an attachment icon at the top of the compose body, not inline as text.

Step 4: Add your recipient, subject, and any context, then send: The attached message is self-contained. Your recipient can open it as a separate email, with the original sender, timestamp, and any prior replies intact.

A few things worth knowing before you hit send:

• You can drag multiple emails from the message list in one go. Select them with Ctrl+click, then drag the group into the compose window. Each lands as a separate .msg file.

• Attaching files and folders in Outlook follows a similar drag-and-drop logic, so the muscle memory transfers.

• Microsoft 365 caps total attachment size at 20 MB for Outlook on the web and 25 MB for the desktop client. A long thread with embedded images can hit that ceiling faster than expected.

If you need to send a thread without editing it, the ribbon method is quicker. The next section covers automatically forwarding emails in Outlook and the "Forward as Attachment" option as a distinct alternative.

How to forward an email as an attachment in Outlook

The Forward as Attachment method is the faster option when you need to send a thread exactly as-is, without editing or adding context inline.

Here is how to do it:

1. Select the email you want to attach in your message list. Do not open it.

2. Go to the Home tab in the ribbon.

3. Click the dropdown arrow next to the Forward button.

4. Select Forward as Attachment. Outlook creates a new compose window with the original message embedded as a .eml file.

5. Address your new email, add any covering note, and send.

This works the same way across Outlook 2019, Outlook 2021, and Microsoft 365 desktop. The ribbon location does not change between versions, which makes it reliable to teach across a mixed team.

The key difference from drag-and-drop: you never touch the original message. There is no risk of accidentally moving it out of your inbox, which matters when you are working through a shared mailbox or a monitored folder.

If you want to understand what this attachment type actually represents to the recipient, what attaching mail in Outlook actually means covers that in detail. For broader attachment handling, the guide on attaching files and folders in Outlook is worth bookmarking.

How to attach multiple emails to one email in Outlook

Attaching multiple emails at once saves the most time when you need to bundle a project thread or send several client messages in a single handoff. The process is straightforward, but most guides only show you the one-at-a-time version.

To attach multiple emails to one email in Outlook, start by opening a new compose window. Then, in the message list:

1. Click the first email you want to attach.

2. Hold Ctrl and click each additional message to build a batch selection. If the emails are consecutive, click the first, hold Shift, then click the last to select the range at once.

3. Drag the selected group directly into the body of your compose window.

Each message lands as a separate .msg attachment. A batch of five emails takes about ten seconds this way, versus reopening the compose window five times.

This drag-and-drop method works in Outlook desktop on Windows (including Microsoft 365, Outlook 2019, and Outlook 2021). Mac users running the new Outlook for Mac can also drag from the message list, though the classic Outlook for Mac does not support it reliably. Outlook on the web does not support drag-to-attach from the message list at all, so web users need to save each email as a file first.

One practical limit: Microsoft 365 caps total attachment size at 20 MB for Outlook desktop and 25 MB for Outlook on the web. A batch of long email threads with inline images can hit that ceiling faster than expected. If you are regularly bundling large threads, it is worth understanding what attaching mail in Outlook actually means before the send fails.

For a broader look at handling files alongside messages, the guide on attaching files and folders in Outlook covers the full picture.

How to attach an email as a PDF in Outlook

Outlook does not have a one-click "export to PDF" button, but you can produce a clean, static copy of any email in two minutes using tools already on your machine.

Print to PDF is the faster route. Open the email, press Ctrl+P, then select "Microsoft Print to PDF" as the printer. Hit Print, name the file, and save it. You now have a PDF that preserves the full header, sender address, timestamps, and body text exactly as they appeared.

Save As PDF works if you have Word in your Microsoft 365 subscription. Open the email, go to File, then choose Save As. In the format dropdown, select PDF. This route gives you slightly more control over page layout before saving.

Once you have the PDF, attaching it follows the same process as attaching files and folders in Outlook: compose a new message, click Attach File, and browse to the saved PDF.

A PDF is the right choice when the recipient needs a record they cannot accidentally edit, when you are archiving a thread for compliance, or when the original .msg format might not open on the recipient's device.

One practical note: PDF file sizes vary with email length and embedded images, so keep the next section's size limits in mind before attaching several at once.

Outlook attachment limits and what to do when you hit them

The Outlook attachment file size limit sits at 20 MB for Outlook desktop (Microsoft 365) and 25 MB for Outlook on the web. When you attach multiple emails as .msg files, each one can run 2–5 MB depending on embedded images and prior thread history. Attach three or four of them and you will hit the cap before you realize it.

Two workarounds cover most situations.

1. Use OneDrive instead of attaching directly: Save the .msg files to a OneDrive folder, then share the folder link inside your message. The recipient gets everything; you stay well under the limit. This also works when you need to attach multiple emails in Outlook to a single thread without inflating the file size.

2. Compress before sending: Select all the .msg files in File Explorer, right-click, and choose "Send to > Compressed (zipped) folder." A folder of five emails that totals 18 MB often compresses to under 10 MB. Attach the zip normally.

If you are unsure whether the issue is size or something else, the next section covers the three errors that cause attachments to arrive as inline text or get blocked entirely, which is a separate problem from the limit.

For broader context on what attaching mail in Outlook actually means, that post explains how Outlook handles different file types under the hood.

Common mistakes when attaching emails in Outlook

Three mistakes account for most of the frustration when you try to attach an email as an attachment in Outlook rather than forwarding it inline.

Dragging from the wrong view: Dragging an email from the reading pane copies inline text, not an .msg file. Drag from the message list instead. That distinction is covered in detail in what attaching mail in Outlook actually means.

Using Forward instead of "Forward as Attachment:" A standard forward pastes the original message as quoted text. To forward email as attachment in Outlook, right-click the message and select "Forward as Attachment" — or use the More menu in the ribbon. The recipient gets a proper .msg file, not a text block.

Ignoring cumulative size: Attaching several threads can quietly push a message past the 20 MB limit on Outlook on the web. If you're attaching files and folders in Outlook alongside email attachments, check the total before sending. Use OneDrive links for anything that might tip the limit.

Closing

Attaching emails in Outlook works best when you match the method to your goal: drag-and-drop for speed, Forward as Attachment for safety, bulk selection for batches, and PDF export for static records. The real time sink isn't the attach itself—it's the back-and-forth loop of forwarding threads, waiting for replies, then attaching and re-forwarding the same conversation again.

If you're managing client handoffs or sales escalations where full conversation history matters, Evox syncs your email threads automatically so the manual attach-and-forward cycle disappears entirely. Your team sees the complete thread in context, without the file management overhead. Ready to eliminate the attach-and-forward loop? Start a free trial with Evox today.

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