Four attempts, one cause, and it is not obvious
Attempts
4
Cause
A file type size limit
Error message
Unhelpfully vague
TransactionalService & account
A proactive answer sent because of observed difficulty.
Illustrative example. Replace the fictional sender, dates, amounts, locations, and account details before use.
Responsive design preview
Compare the desktop and mobile compositions, or unfold the full design. The complete starting copy remains readable below.

Auto follows your screen width. Scroll inside the frame to inspect the complete email.
A reviewed browser rendition of the help article suggested structure. It is not a send receipt or an inbox-placement claim.
Want to change the copy and style?
This page is a read-only reference. The five hands-on studios let you edit a local preview, compare desktop and mobile, and review every change before continuing.
See editable templatesMessage anatomy
The error message says the upload failed. The actual reason is a size limit on one file type, which the message does not mention.
Complete starting copy
Moosewave MCP
The brief asks for a new draft and stops before send.
Connected work