intercom messenger "message failed to send" attachment size limit

TL;DR

When an Intercom message fails to send because of an attachment, the file is over the size limit for messenger attachments. Shrink the file, split it, or link to it instead of attaching it. For recurring large files like logs and exports, linking to hosted storage beats attaching every time and keeps conversations searchable.

The query

intercom messenger "message failed to send" attachment size limit

Use this when

• Messages fail to send when attachments are added
• Agents report the send button doing nothing on large files
• Customers cannot receive files you send
• You are documenting attachment workflows

Not for

• Messages failing without attachments (deliverability)
• Blocked file types (different error)
• Conversation assignment or routing
• API-based message sending limits

Steps

1. Confirm the size limit and the file size

Check the current messenger attachment size limit and the actual file size. Limits change over time, so verify the current number rather than relying on memory.

Expected output: file size versus the current limit, overage quantified.

2. Compress or convert the file

Images: export at a lower resolution or convert to a compact format. Documents: compress or remove embedded media. Logs: trim to the relevant section instead of sending the whole file.

Expected output: file under the limit, content intact.

3. Link instead of attaching for large or recurring files

Upload to your file storage and send a link. This works for any size, keeps the conversation thread readable, and gives you access control and expiry that attachments lack.

Expected output: shareable link sent, attachment avoided.

4. Split multi-file sends

If several files together exceed practical limits, send them across messages or bundle the small ones and link the large one. Do not make the customer download one giant archive when they need one file.

Expected output: files delivered in digestible pieces.

5. Write the team convention

Document when to attach versus link, where to host linked files, and link expiry policy. Agents should not improvise this per ticket.

Expected output: a written attachment convention the team follows.

Template: the reply

Hi [Name], the file is [size], which is over the messenger attachment limit of [limit].

I have put it here for you: [link]. The link works for [expiry period].

If you need it another way, let me know and I will resend it split into smaller parts.

Variant phrasings

intercom attachment too large

Steps 1 and 2. Check the limit, shrink the file.

message failed to send with file intercom

Steps 1 through 3. Size check, compress, or link.

intercom messenger file size limit

Step 1 as the reference answer, step 5 for the team.

Why it happens

Messenger attachments travel through the messaging pipeline with size caps that keep conversations fast and clients stable. Desktop agents happily attach hundred-megabyte exports that the pipeline was never meant to carry. The failure is silent-ish because the composer accepts the file and the send fails.

Edge cases

• Mobile customers: large attachments are worse on mobile data. Link with a preview when possible.
• Sensitive files: linked storage needs access control. Do not link confidential files from public buckets.
• Link expiry: set expiry and say so, or customers return months later to dead links.
• API-sent attachments: the same limits apply through the API. Check size before sending programmatically.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstNMBMqVXWzhaFknO1rLkXw

Resolved from the public thread: https://vectle.com/posts/pstNMBMqVXWzhaFknO1rLkXw

Thread query: intercom messenger "message failed to send" attachment size limit

TL;DR: When an Intercom message fails to send because of an attachment, the file is over the size limit for messenger attachments. Shrink the file, split it, or link to it instead of attaching it. For recurring large files like logs and exports, linking to hosted storage beats attaching every time and keeps conversations searchable.