How to add attachments in email

In this document, we will explain how to add a single or multiple attachments in your email.

You can add static as well as dynamic attachments to emails

There is no limit to the number of attachments. However, maximum size of the attachment(s) should be 10MB. We support the following file extensions: .jpg, .jpeg, .png, .gif, .pdf, .mp4, .doc, .docx, .xls and .xlsx

On clicking on the attach button (highlighted below) on the to right corner of the either Email editor, you will see:

  • Upload Files: Allows you to attach files from the system. This then stays as a static attachment in the body of the email and is sent along with the email as an attachment every time it’s triggered.

  • Dynamic Placeholders: Allows you to include dynamic files within the email, when the notification event is triggered. You can use placeholders to specify the:

    • File Name - Provide a static value like ‘Invoice.pdf’ (if you are testing it manually) or a placeholder like {{attachment.filename}}(if your are triggering notification event via API)
    • Type - Select the file type from the dropdown or you can enter a placeholder like {{attachment.filetype}} You can see all the MIME types here
    • URL - Provide a static URL or Dynamic URL using a placeholder like {{attachment.presigned_url}}. The URL should be wither pre-signed or public URL.

Please note that if you are using Presigned S3 URL, then the URL should trigger a download of the file immediately when opened.

Placeholders should be used if the attachment information is dynamic (for instance, a personalized attachment depending on the recipient). Typically such attachments are sent via an API call. To send dynamic attachments in the event payload, make sure that the data section of the payload has an object called attachment as shown below.

For file type, use MIME types depending on your attachment’s file type
Send Attachment via Email
1curl -X POST 'https://api.fyno.io/v1/<WorkspaceID>/event' \
2-H 'Authorization: Bearer <API_KEY>' \
3-H 'Content-Type: application/json' \
4-d '{
5 "event": "EmailWithAttachments",
6 "to": {
7 "email": "xyz@gmail.com"
8 },
9 "data": {
10 "attachment":
11 {
12 "presigned_URL": "<presigned_URL>",
13 "filename": "<attachment_file_name>",
14 "filetype": "application/pdf"
15 }
16 }
17}'

In the above command:

1Replace <WorkspaceID> with your actual Workspace ID.
2Replace <API_KEY> with your actual API key.
3Replace <presigned_URL> with the Presigned URL of your file.
4Replace <filename> with the name of the file attached.
You cannot use only numeric values as placeholder keys!

How to add multiple attachments?

To add multiple attachments in email, add them in the placeholders as shown below.

1For file 1, you can give the below placeholders,
  • Filename - {{attachment.0.filename}}
  • File Type - {{attachment.0.filetype}}
  • Content - {{attachment.0.presigned_URL}}
2Click ‘Add Key’
3For file 2, you can give the below placeholders
  • Filename - {{attachment.1.filename}}
  • File Type - {{attachment.1.filetype}}
  • Content - {{attachment.1.presigned_URL}}
4You can keep adding as many files. The total file size should not exceed 10MB.
Please note that the content can be base64-encoded content or a Presigned URL

Configuring File Attachments Using Dynamic Mode

Dynamic mode is used when the number of files is not fixed and is provided at runtime as a JSON array (for example, from a previous step’s output).

Instead of manually adding File 1, File 2, File 3, and so on, you define mappings that tell the system:

“For each item in this array, get the file name from here and the URL from there.”

When to Use Dynamic Mode

Use Dynamic mode when:

  • The number of files varies per execution.
  • Files come from an API response, loop, or previous ste.
  • You don’t know in advance how many files there will be.

Dynamic File Attachment Fields

This section explains all fields used to configure dynamic file attachments.

FieldPurposeHow to ConfigureExample
Number of FilesEnables array-based (dynamic) file creation.Select Dynamic.
File MapperDefines one template mapping that applies to every item in the array.Configure once; the system automatically applies it to all items.
File Name (Dynamic)Specifies where to get the file name for each item.Reference the array item using a placeholder.{{files.0.filename}} or {{array_path.0.filename}}
MIME TypeSpecifies the type of file being attached.Reference a placeholder that resolves to a valid MIME type (not a file extension).{{files.0.mime_type}}image/png, application/xml
URL (Dynamic)Specifies where to get the file URL for each item.Reference the array item’s URL field.{{files.0.url}}

Important Notes

  • Dynamic placeholders must strictly follow the a.0.b format (for example, {{documents.0.name}}).
  • The .0. segment is required and acts as a schema hint that allows the system to identify array items.
  • Nested arrays or nested objects are not supported.
    If the filename or URL is not a direct property of the array item, dynamic mapping will not work.

Sample Body

1{
2 "documents": [
3 {
4 "name": "a.pdf",
5 "link": "https://x/a.pdf",
6 "mime_type": "application/pdf"
7 },
8 {
9 "name": "b.pdf",
10 "link": "https://x/b.pdf",
11 "mime_type": "application/pdf"
12 }
13 ]
14}

Dynamic Field Configuration

  • File Name (Dynamic): {{documents.0.name}}
  • MIME Type: {{documents.0.mime_type}}
  • URL (Dynamic): {{documents.0.link}}

Result

Two files are automatically added:

  • a.pdf
  • b.pdf