File Size Limits for Attachments in SMS and Email

Overview

This article explains the file size limits for attachments in both SMS and email messages sent through your CRM. It also covers a powerful enhancement available in Conversations that simplifies sending larger files by automatically using Media Library links and generating video thumbnails to increase engagement.

Key Benefits of Understanding File Size Limits

Knowing the attachment size limits helps you avoid failed message deliveries and ensures your communications are optimized for both deliverability and recipient engagement.

• Prevents delivery issues caused by oversized files
• Ensures compliance with MMS and email provider regulations
• Simplifies file management using the built-in Media Library
• Boosts open and click-through rates with interactive video thumbnails
• Reduces manual effort and eliminates the need for third-party file hosting services

Impact on Users

• Reduces the need for manual workarounds like file compression or external hosting
• Speeds up the attachment process with direct uploads from your device
• Improves engagement by making emails more visually appealing and interactive
• Ensures smooth delivery across both SMS and email by automatically managing size limits

SMS Attachment Size Limits

SMS messages can only contain text. To include attachments such as images, videos, or audio files, you must use MMS (Multimedia Messaging Service), which is supported differently depending on your phone number type and carrier. When you attach a file to an SMS message, it is automatically converted to MMS.

The following file types are supported for MMS attachments:

• JPEG
• PNG
• GIF

Please note: Some additional file types like MP3, MP4, and PDF may work depending on the carrier and recipient device.

Carrier-Specific File Size Limits for MMS

The recommended best practice is to keep MMS attachments under 500 KB to ensure successful delivery across all carriers.

Different carriers have different maximum size limits for MMS attachments:

• AT&T: 1.0 MB for Long Code, 0.6 MB for Toll-Free, 0.6 MB for Short Code
• T-Mobile: 1.5 MB for Long Code, 0.6 MB for Toll-Free, 1.0 MB for Short Code
• Verizon: 1.0 MB for Long Code, 0.6 MB for Toll-Free, 1.2 MB for Short Code

Short Code, Toll-Free, and Long Code Support for MMS

As of October 2022, Toll-Free numbers support MMS attachments. Before this date, they supported SMS only.

• Long Code (10DLC): Supports MMS with recommended maximum size of ~500 KB – 1 MB
• Short Code: Supports MMS with maximum size up to 5 MB
• Toll-Free: Supports MMS (since October 2022) with maximum size up to 5 MB

Email Attachment Size Limits

Attachment limits for email depend on the email provider used. Exceeding these limits can cause emails to bounce or become undeliverable.

File Size Limits by Provider

The CRM's email composer allows up to 20 MB in attachments. Files larger than this size will be automatically uploaded to the Media Library and sent as clickable links instead of direct attachments.

• Gmail: 25 MB
• Yahoo Mail: 25 MB
• Outlook.com: 10 MB
• Mailgun: 25 MB

How to Upload Attachments in Conversations

Uploading files directly in the Conversations composer has been made easier and more flexible with the updated attachment workflow. Whether you're sending an SMS or an email, you can now upload files from your device or choose from your Media Library — all from within the message composer.

This process eliminates the need to manually compress files or use third-party hosting platforms, streamlining your workflow and improving the customer experience.

Step-by-Step Process for Uploading or Attaching Files

1. Access the Attachment Options

Open a conversation under the Conversations tab and click the three-dot icon (•••) in the message composer.

2. Choose Your Attachment Source

After clicking on the three-dot icon, select "Attach Files." You'll see two options:

• Upload from System – choose a file from your local device
• Choose from Media Library – select a previously uploaded file

3. Automatic Handling for Large Files

If the file exceeds 20MB (for email) or any size for SMS, the CRM will automatically upload it to the Media Library and insert a clickable link into your message. This ensures that your message is delivered without hitting size limits.

Important: Video Uploads Get Auto-Generated Thumbnails

When uploading a video file through the Media Library, the CRM will automatically generate a GIF thumbnail to be shown in your email, making your message more engaging and clickable.

Paste Attachments from Clipboard

Instead of opening the attachment menu, you can attach files by pasting them directly.

1. Copy a supported file or image on your computer
2. Click inside the message composer in Conversations
3. Press Ctrl + V (Windows) or Cmd + V (Mac) or right-click and select Paste

The pasted file attaches instantly to the current message and respects the same size limits and media handling rules described above.

How to Send Larger Files

• Upload directly via the email/SMS composer – files larger than 20MB are auto-hosted via Media Library and inserted as links
• Use cloud hosting only if needed outside the CRM
• Add videos via Media Library for interactive thumbnails

Frequently Asked Questions

Q: What happens to files over 20MB?
They are automatically uploaded to the Media Library and sent as clickable links.

Q: Can I upload attachments directly from my device?
Yes! You can choose between uploading from your system or browsing the Media Library.

Q: Can I attach videos to an SMS?
Yes, videos are sent as hosted links — not embedded files — to avoid delivery issues.

Q: Do Toll-Free numbers support MMS?
Yes! Since October 2022, Toll-Free numbers now support MMS and attachments.

Q: Will video attachments generate a preview in emails?
Yes — GIF thumbnails are automatically generated for video files uploaded via Media Library.