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Custom Attachments for Individual Contacts

Custom Attachments for Individual Contacts


Purpose


Custom attachments let you attach different files per contact based on a URL stored in each contact's custom field. For example, you can send a personalized resume, proposal, or document to each prospect by storing the file URL in a custom attribute. This article explains how to set up custom attachment variables and use them in your email steps. It also covers how to create a downloadable link when your files are stored in Google Drive.


Prerequisites


  • A campaign with contacts
  • The files you want to attach (hosted at a URL that returns the file directly — not an HTML viewer page)


Steps


1. Add a Custom Attachment Variable to Your Contact Config


  1. Go to your campaign and open Contacts.
  2. Open Global Settings (or the contact config for your campaign).
  3. Under Custom Variables, click Add Custom Variable.
  4. Enter a name (e.g. resume_url or proposal_url).
  5. Set the Type to attachment.
  6. Save the contact config.


The variable will appear as {{resume_url}} (or whatever name you chose) and can be used in your sequence.


2. Add the File URL to Each Contact


Each contact needs the URL of their file stored in the custom field you created. You can do this by:


  • CSV import: Include a column with the variable name (e.g. resume_url) and the URL in each row.
  • Manual edit: Open a contact, go to the Variables or Info tab, and paste the URL into the attachment field.
  • Integration: If you use HubSpot, Zapier, or another integration, map the URL field to your custom attachment variable.


The URL must be a direct link that returns the file when fetched — not a page that displays the file in a browser. For example, https://example.com/document.pdf works. Google Drive view links do not work unless converted to the direct download format (see below).


3. Select the Custom Attachment in Your Email Step


  1. Open your campaign and go to the Sequence tab.
  2. Select an email step.
  3. In the email editor, find the Custom Attachments section (below the body).
  4. Check the box next to the variable you want to attach (e.g. {{resume_url}}).
  5. Save the step.


When SuperSend sends the email, it fetches the file from the URL stored in that contact's custom field and attaches it to the message.



Google Drive sharing links usually open a web viewer instead of returning the file. SuperSend needs a direct download URL. If your files are in Google Drive, follow these steps to create a link that works:


Step A: Get the File ID from your Google Drive link


When you share a file, you get a link like:


https://drive.google.com/file/d/1pjH2U4M8DZ5wONYggVJAGx33rwR5dhL1/view?usp=drivesdk


The File ID is the long string between /d/ and /view. In this example: 1pjH2U4M8DZ5wONYggVJAGx33rwR5dhL1.


Step B: Build the direct download URL


Use this format:


https://drive.google.com/uc?export=download&id=YOUR_FILE_ID


With the example File ID:


https://drive.google.com/uc?export=download&id=1pjH2U4M8DZ5wONYggVJAGx33rwR5dhL1


Step C: Verify the link


Open the direct download URL in a new browser tab. The file should download (or prompt to download) instead of opening in the Google Drive viewer. If it downloads correctly, the link will work in SuperSend.


Step D: Use the link in SuperSend


Paste this direct download URL into each contact's custom attachment field (via CSV, manual edit, or integration). SuperSend will fetch and attach the file with the correct filename and extension.


Expected Result


  • Each contact receives an email with the file attached from their custom URL.
  • Files from direct URLs (e.g. your own server, S3, or Google Drive direct download) attach correctly with the right filename and extension.
  • Recipients can open the attachment without manually adding a file extension.


Troubleshooting


  • Issue: File doesn't attach or attachment has wrong filename/extension.

Fix: Use a direct download URL, not a viewer page. For Google Drive, use https://drive.google.com/uc?export=download&id=FILE_ID, not the /file/d/ID/view format.


  • Issue: "Could not download attachment" error when sending.

Fix: Ensure the file is accessible. For Google Drive, share the file with "Anyone with the link can view." Check that the URL is correct and returns the file (not an HTML page or login screen).


  • Issue: Variable doesn't appear in Custom Attachments.

Fix: The variable must have type attachment in your contact config. Add it in Global Settings or contact config, then save.


  • Issue: Contact has no attachment.

Fix: Ensure the contact's custom field (e.g. resume_url) contains a valid URL. Empty or invalid URLs are skipped.



Updated on: 19/03/2026

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