How to handle email attachments >5MB from Zoho Mail to Zoho Creator via Zoho Flow?

How to handle email attachments >5MB from Zoho Mail to Zoho Creator via Zoho Flow?

Hi Zoho Community,

I'm building an email management system that automatically captures incoming emails from Zoho Mail into Zoho Creator records via Zoho Flow. Everything works fine except for one major blocker — email attachments larger than 5MB.

Current Setup:

  • Zoho Mail receives emails with attachments
  • Zoho Flow triggers on new email
  • Deluge script downloads attachment from Zoho Mail API and uploads to Zoho Creator file upload field
  • Works perfectly for files under 5MB

The Problem: Deluge throws error for files over 5MB:

This is a Deluge memory constraint when using invokeurl to download files.

What I've Already Tried:

  1. Direct Zoho Mail API link — requires OAuth token in header, throws INVALID_TICKET error when opened in browser. Not usable as a clickable download link.
  2. Zoho Mail web URL (mail.zoho.com/zm/#mail/folder/...) — only opens the email, does not trigger attachment download.
  3. Zoho Mail filter → auto-upload to WorkDrive — successfully uploads files to WorkDrive folder (no size limit!), but cannot identify which files belong to which email since multiple emails may have attachments with the same filename.
  4. Zoho WorkDrive API via Deluge — tried searching files by name in WorkDrive folder after filter uploads them, but invokeurl to zohoapis.com/workdrive/api/v1/ returns empty responses even with a fully authorized connection with all scopes enabled.
  5. Zoho Flow native WorkDrive actions — checked all available WorkDrive actions in Flow, but there is no "Upload File" action available.
  6. Zoho Flow native Zoho Mail actions — no "Get Attachments" or "Download Attachment" action available either.

What I Actually Need: A clickable public download link for each attachment that:

  • Works for files of any size (no 5MB limit)
  • Can be stored as HTML in a Zoho Creator rich text field
  • Is accessible by anyone without requiring Zoho login

Questions:

  1. Is there any native Zoho way to generate a public download link for a Zoho Mail attachment without downloading it through Deluge?
  2. Why does the Zoho WorkDrive API via invokeurl in Deluge return empty responses even with all scopes authorized? Is there a correct endpoint I should be using?
  3. Is there a planned update to add "Upload File" action in Zoho Flow for WorkDrive or Zoho Mail?
  4. Would the WorkDrive Email-In feature work here? If I forward the email to a WorkDrive folder email address, can I then reliably identify which uploaded files belong to which email (e.g., via subfolder per Message ID)?

Any help or workaround suggestions would be greatly appreciated!

Environment:

  • Zoho Creator (Deluge)
  • Zoho Flow
  • Zoho Mail
  • Zoho WorkDrive

Thanks in advance!