If you put many elements into a single image, it can become very long. Many versions of Microsoft Outlook (from 2007 to the present) have issues displaying long images.
The Windows desktop version of Microsoft Outlook uses Microsoft Word to render HTML. Since Word is meant for print, not web or email design, it causes emails to look different from what you expected.
The limit for image length in Microsoft Outlook is exactly 1,728 pixels long (18 inches in 96 dpi). Any images over 1,728 pixels long will have the excess clipped off from the top.
If you have any image longer than 1,728 pixels, you should slice it into multiple pieces and make sure every piece is not longer than that.
After that, if you use our drag-and-drop editor, you can add multiple image blocks to it and reconstruct the pieces to look like one image. Remember to remove any padding around the image blocks.
If you code your HTML, you can insert the image pieces into multiple <td> in the same column. Then, add style="display: block" to the <img> tags to remove any space between the pieces. You may also need to set the cellpadding or cellspaceing to 0 in your <table>.
In Windows, you can right-click your image, then click [Properties]. You can find the image dimensions in the [Details] tab.
Another simple way is to check the file size of an image. An image within the acceptable height is usually within a few hundred KB and should not exceed 2 MB. An image may be excessively high if you can’t upload it to our content hosting storage because it exceeds 2 MB.