If you’ve ever tried to email a big file through Outlook and hit a wall, you’re not alone. Most Outlook versions cap attachments at just 20 MB—and even if you're using Microsoft 365, you're still limited to around 150 MB. It’s not much if you're working with visuals, design files, video, or other oversized assets that you might deal with daily.
There are some dull, annoying workarounds—like splitting files or compressing them. But you might still get an embarrassing bounce-back when your file is just too big to send. Dropbox gives you two more professional options:
- Share a live file or folder directly from your cloud storage—ideal for collaborating with clients or teammates
- Use Dropbox Transfer to send a non-editable copy of your file, up to 100 GB
These methods allow you to avoid compression and any disruptions to your workflow when using Outlook. If you’re using Microsoft 365, you can also try the Dropbox integration to make it even easier to keep files moving.
Why won’t my file attach in Outlook?
You’ve got the perfect file ready to send—and Outlook just won’t work. It’s late and you want to get this sent, why won’t it upload? Well, there are a few common culprits behind those frustrating little error messages:
- It’s too large: A common cause, most Outlook accounts cap attachments at 20 MB. Even with Microsoft 365, you’re still looking at a 150 MB file size limit. That’s barely a handful of large images or a pretty short video clip.
- You’re using an outdated version of Outlook: Sometimes, older versions may not support modern file handling features—or large attachments at all. This is often a problem when using Outlook’s old mobile apps.
- Your internet connection is shaky: A spotty connection can interrupt uploads mid-way—especially if you're trying to send bigger files that take a while to upload. This is a big frustration, especially when you’re busy.
- The file type is restricted: Some file types (like .exe and certain database files) are blocked for security reasons. This is because a lot of viruses and malware exploit these types of files—ruining it for everyone.
- Your mailbox is full: Lastly, If you’re close to your storage limit, Outlook won’t let you send anything new. This is often a problem for people using free versions of Outlook and OneDrive.
None of these problems affect Dropbox Transfer. It’s built to send large files of any size or format—just upload, generate a secure link, and send it from Outlook. No stress, file compression, or email bounce backs, just professional delivery.
4 ways to send large files through Outlook
If you’ve ever clicked send in Outlook and got an error, or a bounce-back hours later, you know how annoying it is to send big files. But fear not, there are several simple workarounds to try—let’s start with the easiest option:
1. Use Dropbox to create a secure link to the file and share it
The simplest method of sharing a large file in Outlook—providing you don’t mind the recipient having access to your own copy of the file—is to generate a secure link and send it in an email. Here’s how to do it directly from your cloud storage in a few clicks:
- Upload a file to your Dropbox account, then right-click and select ‘Copy link’
- Paste that link into your Outlook message—no need to compress, zip, or split—and send it over, whether the recipient has a Dropbox account or not
This is an excellent method as there’s no need to worry about attachment limits or whether your recipient uses the same tool. You’re sharing the live version of the file, so if you’re collaborating, that’s a huge plus.
If you need to limit what someone can do with a file, Dropbox lets you add password protection, expiration dates, or view-only permissions to links. Whatever the type of file, you can keep it crisp, secure, and under your control.
As an added bonus, link sharing works everywhere—other email clients like Gmail, Slack, Teams, web browsers—so it’s as versatile as you or your team needs.
2. Use the Outlook integration
Dropbox includes many potential app integrations for your favorite tools—so it’s ideal if you’re the kind of person who doesn’t want to change how they work. These include several for working more efficiently in Microsoft tools.
If you live in Outlook all day, the good news is that the Outlook integration makes it seamless to pull files directly from your cloud storage into emails. Just select what you want to share, insert the link right in your draft, and send.
It’s great for teams working on tight timelines who need to move fast—without changing how they already work. No switching tools, no uploading twice, no drama.
3. Use Transfer for large file deliveries
Dropbox Transfer is your go-to for final file handoffs—like polished videos, design deliverables, or any other large-format file. It’s spectacularly simple but also offers fast uploads and downloads with the highest levels of security.
- Simply head over to dropbox.com/transfer
- Upload your file and send it to the recipient
You can send files up to 100 GB (or 250 GB with Dropbox Replay Add-On), track downloads, confirm delivery, and brand the transfer with your logo for a polished, professional touch. No need to worry—just send and go.
4. Use Outlook and OneDrive—as far as it works
Outlook and OneDrive can work together to send bigger files—but only up to a point. You’ll likely hit limitations if your files are extra-large, the formats are unsupported, or the recipient’s permissions aren’t set correctly.
Some professionals also report formatting changes or file compression. If you need to guarantee pixel-perfect delivery, you might want to look elsewhere. With Dropbox, what you send is always exactly what your client sees.
Tips for success when sending files through Outlook
Despite the limitations, if you’re sending large files through Outlook, it’s not just about making the email go through—it’s about making it look polished and easy to navigate for the person on the other end.
Here are a few quick tips to make your big file delivery look as professional as the work you’re sharing:
- Add context to your email—instead of pasting a Dropbox shared link, include a short explanation of what the file is, then hyperlink it to some clean, descriptive text
- Label everything clearly—use file names and version numbers that make sense because naming structure goes a long way when a client is juggling multiple deliverables
- Send a folder link when possible—if you're sharing a batch of files share a folder instead of individual links, which keeps everything together and makes it easier for the recipient to stay organized
Outlook can still be your go-to for big file sharing—as long as you use Dropbox and a few thoughtful touches to help deliver your files successfully and with a sense of professionalism.
Frequently asked questions
You can consider putting files into a ZIP archive or using online tools to make them smaller. However, these tools might lower the file quality—something that’s not acceptable in many cases. If you want to maintain quality, a better choice is to use your Dropbox cloud storage to share a link to the file with no need to compress it.
The best way to get past the Outlook attachment limit is to use a cloud storage service like Dropbox. This way, you can share a link to the file instead of attaching it. This is easier than trying to fit a big file into the 20 MB limit that most Outlook versions have. Dropbox lets you upload large files and generate a secure link, which you can then share—just copy the link, paste it into your Outlook message, and send.
You can't do this directly in Outlook. However, with Dropbox Transfer, you can track when people download your files—to make sure they are received. You can also track who views your files or add a password. This gives you more control, especially for work you send to clients or files that are only useful for a short time.
You can’t send a large file through Outlook alone. However, you can use Transfer or send a shareable link from your Dropbox account. You don’t need to compress or split your files, just upload, create a link, and add it to your Outlook email—the recipient doesn’t even need a Dropbox account to get the file. This keeps files in their original quality and makes it easier for your client. Plus, it won’t fill up anyone’s inbox.
Send files through Outlook with confidence using Dropbox
Outlook wasn’t built for sending hefty videos, massive images, large database files or any other cumbersome digital assets. With Dropbox in your corner, you don’t have to stress about file size limits.
With Dropbox, you avoid accidental file compression, frustrating bounced emails, and workflow disruptions in Outlook. Simply generate a secure link, drop it into your message, and hit send—or use Dropbox Transfer.
Want to make sending large files the easiest part of your day? Get a free Dropbox account and try our Outlook integration today—faster, safer, and built for creative teams who need their work delivered exactly as intended.
