Try this:
In your System Core module, under the Quota Config TAB....
add the word: iframe ...to the list of "allowed html tags"... for the quotas you want to allow it for.
-See the top drop-down list of your various quotas, for which you can allow/disallow certain text permissions as you choose for different quotas. Obviously you may want to allow admins to have more html options than regular members. For example, I don't allow regular members to use H1 titles, or 'form' in their posts.
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...just another satisfied Jamroom customer.
Migrated from Ning to Jamroom June 2015
updated by @strumelia: 08/26/16 01:05:09PM