In Telligent Enterprise, you can embed images in the post via the editor, using the Insert Image button.
To change settings for how attachments are handled, including file extensions, for all forums:
Navigate to Control Panel Dashboard > Forum Administration > Configuration > Global Forum Settings > Attachments.
To modify the types of files that community members can attach to a forum post, add or remove the file extension from Allow File Extension Types.
To put no limit on file attachments, set Max File Size to 0. To specify a different limit than the default 64KB, specify the maximum file size.
Note: If using Mail Gateway for two-way email fidelity and the forum from which you’re working with has the Mailing List functionality turned on (that is, it has a set email alias), all of the attachments from that forum are saved in that group’s primary media gallery (that is, the first media gallery listed for that group).