- Why your customer got a link instead of the file
- Inbound and outbound limits side by side
- What happens at each limit
- Email encoding adds a third to every file
- When links appear even for small files
- Workarounds when a file won't fit
- How another help desk handles attachments
- My advice for support teams
- Frequently asked questions
Zendesk accepts a single inbound email or web form attachment of up to 50 MB. Outbound email attachments are limited to 7 MB per file and 10 MB in total, and anything over that is sent as a link instead. The limits can't be raised, so very large files need hosting elsewhere.
Why your customer got a link instead of the file
A customer writes back saying they can't see the attachment, only a download link. Or a ticket arrives with the message but without the screenshot they swore they attached. Both come down to the same thing: the help desk has separate limits for files coming in and files going out, and the outbound one is much smaller than the headline number.
Inbound and outbound limits side by side
| Item | Limit | Applies to |
|---|---|---|
| Inbound single file (email, web form) | 50 MB | Support tickets |
| Outbound email, single file | 7 MB | Email notifications with real attachments |
| Outbound email, all files combined | 10 MB | Email notifications with real attachments |
| Single linked file | 50 MB | Linked attachments |
| Files per ticket | Up to 500 | Authenticated end users (email, web form, customer portal) |
| Anonymous web form attachments | 5 per request | Unauthenticated end users |
All six rows come from the Zendesk Help Center articles on attachment limits and web form attachments.
What happens at each limit
Coming in
If a customer sends a file over 50 MB, the ticket is still created, just without the attachment. Nobody gets an error on your side, so you'll usually only find out when the customer asks whether you've looked at their file.
Customers who aren't signed in have a hard-coded limit of five attachments per web form request, as spam prevention. Signed-in customers can submit up to 500 files at 50 MB each. If your customers often send batches of photos or documents, asking them to sign in first saves a lot of back and forth.
Going out
A single outbound file over 7 MB is sent as a linked attachment instead. Once all the files on a reply go past 10 MB combined, the extra ones go as links too. A linked file can be up to 50 MB, and a file over 50 MB shows an error and isn't attached either way.
Email encoding adds a third to every file
Here's the part the 50 MB headline hides. The Zendesk Help Center notes that email encoding, known as MIME, expands an attachment's size by 33 percent when it's sent by email. So a file that looks comfortably under the limit on your desktop can go over it once it's in an email. A 6 MB PDF, for example, becomes roughly 8 MB in transit, which is over the 7 MB outbound cap.
Put that together with the outbound limits and you get the most common complaint: files over 7 MB, or more than 10 MB combined, quietly turn into download links. The customer sees a link where they expected a file, and it looks like something broke.
When links appear even for small files
Attachments are linked by default. To send real files in email notifications, an admin has to switch the setting on in Admin Center under Objects and rules, Tickets, Settings. If customers still get links for small files after that, check two things: that Include attachments in emails is on, and that your triggers don't use the {{ticket.comments_formatted}} placeholder. Swapping it for {{ticket.latest_comment_rich}} is the fix the help centre suggests.
One more odd failure: GIFs with a very large number of frames can time out on upload. Recreating the GIF with fewer frames sorts it.
Workarounds when a file won't fit
The help centre says plainly that the attachment limits can't be increased. The suggested workarounds are to host the file elsewhere and send a hyperlink, or to use a file-sharing app such as the Box app, which Zendesk names as an option for files over the limits.
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If you send big files from your own inbox as well, this guide on getting large files through Gmail covers the same problem there.
How another help desk handles attachments
Freshdesk sends and receives email attachments up to 20 MB per conversation on Blossom and above, and 15 MB for Sprout and trial accounts. That's a higher outbound ceiling, though lower than 50 MB coming in. For a wider look, see my picks of the best help desk software for small businesses and this round-up of other support platforms worth comparing.
My advice for support teams
Plan around 7 MB, not 50 MB. Turn on real attachments in Admin Center, fix any trigger using the formatted comments placeholder, and keep anything over about 5 MB in cloud storage so you can send a clean link on purpose rather than by accident. Ask regular senders to sign in so they're not stuck at five files.
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Frequently asked questions
What is the Zendesk attachment size limit?
50 MB for a single inbound file by email or web form, and 7 MB per file and 10 MB total for outbound email attachments.
Can I increase the limit?
No. Zendesk says the limits can't be increased.
What happens if a file is too big?
Inbound over 50 MB, the ticket is created without it. Outbound over the email limits, it's sent as a link.
How many files can a customer attach?
Signed-in end users can attach up to 500 files; anonymous web form users are limited to five.
How do I send a very large file?
Host it elsewhere and send a link, or use a file-sharing app such as Box.
