Summary
If campaigns sent to Outlook or Gmail contacts arrive with blank or partially missing content, it is most likely related to the Classic Designer in ActiveCampaign.
Resolution
To resolve this issue, create your campaign using the Email Designer (launched in 2022) as it generates less HTML and does not have this issue. There is no way to prevent this from happening in the Classic Designer.
Cause
This happens because the Classic Designer creates HTML tables as you design. It is possible for several tables to nest into each other as you move and create blocks in the designer. Once sent, Outlook and Gmail can become overwhelmed with rendering these nested tables and therefore show as blank or missing.
Note that this is a separate issue from Gmail “clipping” messages.