File Attachment Settings
From XMBdocs
File Attachment Settings are the seventh group on the Settings Page.
This article provides more information about each setting in the File Attachment Settings group.
Some of these settings are described in even greater detail in New settings for XMB 1.9.11.
Maximum Attachment size (in bytes):
Sets the size of the maximum attachment allowed in bytes. Any attachment larger than this size will not attach to the post.
Show Thumbnails in Posts:
When enabled, attached image files will be represented by thumbnail images inline with the text of the post. When disabled, image file attachments are treated like a generic binary file and represented only by a download link.