Zoho Desk lets you control which file types agents and customers can attach to tickets and messages, and you can configure templates to include attachments automatically. This guide covers both attachment security controls and template attachment management.
Why this matters
If your team exchanges sensitive files or you need to prevent malware risks, controlling attachment types is essential. Administrators in Enterprise editions can restrict file formats like executables or archives. Additionally, if you send templated responses or documents regularly, embedding attachments in templates saves time and ensures consistency across your support workflow.
Step-by-step
Step 1. Access attachment controls (Enterprise only)
Navigate to your Zoho Desk admin panel and locate the Security Settings section. Here you'll find the attachment control option, which manages files, documents, and images that customers or agents upload and associate with support tickets [1]. This feature is available only in the Enterprise edition [3].
Step 2. Define allowed file types
Within attachment controls, specify which file formats your team can exchange. You can block potentially harmful formats such as executable files (.exe) or compressed archives (.zip) to reduce malware and virus risk [3]. The system will then enforce these restrictions across all communication channels—email, chat, and ticket uploads.
Step 3. Set up template attachments in email templates
When creating or editing an email template in Zoho Desk, you can include attachments. If you're using Zoho Writer merge templates, you can attach files collected from Zoho Forms by selecting the Forms file upload field as a merge field in your email attachment settings [4]. This allows you to automatically send customer-submitted files as attachments without manual intervention.
Step 4. Configure conditional attachments (Writer templates)
For advanced use cases, Zoho Writer merge templates support conditional attachments. You can set rules so that specific documents attach only when conditions are met—for example, attaching a certificate of origin only to export orders, or salary details only to certain employee roles [4]. This reduces clutter and ensures the right documents reach the right recipients.
Step 5. Set a default template on mobile
If you use the Zoho Desk Android app, you can set a preferred email template as default directly from the app. Open Settings, then navigate to the Email Template section and mark your choice as default [7]. This template will then auto-apply in Blueprint replies and can be updated anytime.
Step 6. Verify attachment size and format limits
Be aware that attachment limits vary by Zoho product edition. For example, in Zoho FSM (which shares similar attachment handling), the Standard edition supports up to 10 attachments with a combined size of 5 MB, while the Free edition allows only one attachment up to 3 MB [2]. Supported file types include .jpg, .png, .gif, .jpeg, .tiff, .pdf, .docx, .xlsx, .csv, .txt, .bmp, .vcf, .xls, and .xml [2].
Common pitfalls
If an email template is linked to an active email notification, you cannot delete it [2]. Ensure you unlink or disable the notification first. Additionally, if you're using Zoho Writer merge templates with conditional attachments, remember that approved templates with attachments cannot be changed to "None"—you can only update them to another supported attachment type [8].
What to check
- Confirm that your attachment control rules are enforced across all channels (email, chat, ticket uploads) and that blocked file types are rejected consistently.
- Test a template with attachments by sending a test ticket or message to verify files arrive with the correct names and sizes.
- If using mobile, update your Zoho Desk app to the latest version to access the default template feature.
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*This article is provided by Beam Help — independent expert support for Zoho. We are not official Zoho support.*