If you encounter errors while attaching an image to an individual message, mass message, or template, it's highly probable that the issue is due to an unsupported image file type or size.
Is your image file type supported?
The supported image file types include PNG, JPG, or GIF. If your image file is not one of these supported types, then you can use an image file converter to convert the file in to a PNG, JPG, or GIF.
Is your image file too large?
The total size of all images in one message cannot exceed 5MB and each individual image must be no larger than 1.5 MB.