Send large files with Outlook

Q: Why doesn’t my recipient receive my 15 MB attachment?

Exchange servers enforce their own limits, often below 20 MB, and filter certain file types. A download link always gets through, whatever the size.

Q: Does the add-in work in Outlook on the web?

Yes: Outlook for Windows, Mac and the web are all covered, as long as your version supports AppSource add-ins.

Q: How much can I actually send under the Outlook limit?

Microsoft sets the limit at 20 MB per message for Internet email accounts; since attachment encoding adds roughly a third, the real usable size is around 15 MB.

Outlook caps attachments at 20 MB. TransferNow sends up to 5 GB for free: paste the link into your email — or install our official add-in, which replaces the attachment right from Outlook.

Transfer now See the guide

Outlook limit: 20 MB
Up to 5 GB free
Official add-in

Average rating after at least one transfer:

4.8763,165 votes

4.9 / 5 on Trustpilot and Google (20k+ reviews)

Average rating after at least one transfer:

4.8750,000 votes

4.9 / 5 on Trustpilot and Google (20k+ reviews)

The problem

Outlook and attachments: 20 MB, with corporate rules on top

Outlook’s default limit is 20 MB per message — and in companies, Exchange administrators often lower it further, on both the sending and receiving side. Your 15 MB attachment can be rejected by the recipient’s server without you ever knowing.

Add security filtering on top: some file types (archives, executables) are blocked or quarantined. A download link cleanly sidesteps all three obstacles — size, server rules, filters — while keeping full traceability.

Outlook attachment20 MB
Gmail attachment25 MB
TransferNow — free, no sign-up5 GB
TransferNow — with an account500 GB

Logarithmic scale — the exact values are what counts.

The solutions

Three ways to send a large file through Outlook

Attachment, OneDrive or transfer link: what each option means in a professional context.

Comparison of sending methods: maximum size, quality and recipient experience.
Method	Max size	Quality	For the recipient
TransferNow add-inRecommended	5 GB free · 500 GB with an account	Files intact, link inserted in the email	One click, no account
Outlook attachment	20 MB (less depending on IT policy)	Intact	May be rejected or quarantined
OneDrive sharing	Depends on Microsoft 365 quota	Intact	Permissions, Microsoft account often required

The add-in: the attachment, done better

From the compose window, select your files: the upload happens in place and the link replaces the attachment. The recipient gets a normal email — one that always gets through.

The attachment: subject to IT rules

20 MB by default, sometimes 10 on the recipient’s side, filtered file types: the corporate attachment is a minefield as soon as you move beyond a light PDF.

OneDrive: great inside the organization, friction outside

OneDrive sharing shines between colleagues on the same Microsoft tenant. Outside, it often demands an account and permissions — where a transfer link just downloads.

Guide

How to send large files with Outlook?

1
Install the add-in from AppSource
The TransferNow add-in works with Outlook for Windows, Mac and the web — and your administrator can deploy it centrally.
2
Select your files from the message
In the compose window, add files or folders — up to 5 GB for free.
3
The link replaces the attachment
Once the upload finishes, the link is inserted into your email. Hit send: you are notified of every download.

Transfer now See our plans

With TransferNow

Built for your transfers from Outlook

AppSource add-in

TransferNow inside Outlook

Our official add-in (Microsoft AppSource) works with Outlook for Windows, Mac and the web — deployable by your administrator for the whole team.

5 GB free

250 times the Outlook limit

The free tier absorbs the RFP folders, presentations and appendices that attachments reject.

No quarantine

Filters no longer get in the way

The email contains nothing but a link: no attachment to filter, no archive silently quarantined.

Antivirus

Security still comes first

Files are scanned by an antivirus solution before the link goes live — your recipients’ caution is well served.

The free tier, translated into real files

20 MB: the default Outlook limit — sometimes less
5 GB: per TransferNow transfer, for free
3 versions: Outlook for Windows, Mac and web covered
0: attachments stuck in quarantine

Transfer up to 5 GB for free

Frequently asked questions

How do I send a file larger than 20 MB with Outlook?

Install the TransferNow add-in from Microsoft AppSource: select your files from the message, and the link replaces the attachment — up to 5 GB for free.

Why doesn’t my recipient receive my 15 MB attachment?

Exchange servers enforce their own limits, often below 20 MB, and filter certain file types. A download link always gets through, whatever the size.

Does the add-in work in Outlook on the web?

Yes: Outlook for Windows, Mac and the web are all covered, as long as your version supports AppSource add-ins.

Can my administrator deploy the add-in for the whole team?

Yes: through the Microsoft 365 admin center, the add-in can be installed centrally for all users.

How much can I actually send under the Outlook limit?

Microsoft sets the limit at 20 MB per message for Internet email accounts; since attachment encoding adds roughly a third, the real usable size is around 15 MB.