Why can't I send my campaign with video attachments?
In this article, we explain why sending campaigns with videos in Atom may fail, even if the file appears to be the correct size and format.
❓ Frequently asked question or initial context
If you receive an error message such as "The file could not be sent because the size is too large or it is damaged" when trying to send a campaign in Atom with a video attached, the problem is likely related to the video file codecs, beyond the size or format.
Atom requires that multimedia files meet certain technical requirements in order to be sent correctly in bulk campaigns.
🛠 Troubleshooting: Step-by-step to identify the problem
Check the file size. Make sure the video does not exceed 15 MB (although we recommend maximum 10 MB files for greater stability).
Make sure the video does not exceed 15 MB (although we recommend maximum 10 MB files for greater stability).
Check the file format. Atom only supports videos in .mp4 format.
Atom only supports videos in .mp4 format.
Analyze the video codecs. Required:Video codec: H.264Audio codec: AAC (Advanced Audio Codec)
Required:Video codec: H.264Audio codec: AAC (Advanced Audio Codec)
Video codec: H.264
Audio codec: AAC (Advanced Audio Codec)
How to check the codecs?On PC:Right click on the video → Properties → DetailsOn Mac:Use the QuickTime app → Command + I
On PC:Right click on the video → Properties → Details
Right click on the video → Properties → Details
On Mac:Use the QuickTime app → Command + I
Use the QuickTime app → Command + I
✅ Possible solutions
Video file conversion:If the codec is not compatible (for example, HEVC or VP9), convert the file toH.264/AACusing tools such as:HandBrake(Windows/Mac/Linux)Clideo Video Converter (online)Any Video Converter
If the codec is not compatible (for example, HEVC or VP9), convert the file toH.264/AACusing tools such as:HandBrake(Windows/Mac/Linux)Clideo Video Converter (online)Any Video Converter
HandBrake(Windows/Mac/Linux)
Clideo Video Converter (online)
Any Video Converter
Reduce the file size:Through compression in HandBrake or platforms likeVEED.io
Through compression in HandBrake or platforms likeVEED.io
📝 Additional notes
Corrupted files, even if they meet the size and codec requirements, can also generate the same error.
Make sure that the file name does not contain special characters or unnecessary spaces.
💼 Practical example or use case
The user tried to send a campaign with a video_event.mp4 file of 12.7 MB, but received the error: "The file could not be sent because the size is too large or it is damaged."
When reviewing the video, it was found to be using the video codecHEVC (H.265). UsingHandBrake, the file was converted to codecH.264, keeping the.mp4 formatand the same size.
After replacing the file in the campaign, the sending was successful.
📞 When to contact support?
If after performing the above steps:
The video meets the requirements and continues to fail,
The system marks the file as "sent" but the contacts do not receive it.
Please contact our support team including:
The name of the campaign
The attached file
Screenshots of the error (if applicable)