One of the conditions to a Rule 506 offering is that the issuer not engage in general solicitation.
The rule is as follows:
c. Limitation on manner of offering. Except as provided in Rule 504(b)(1), neither the issuer nor any person acting on its behalf shall offer or sell the securities by any form of general solicitation or general advertising, including, but not limited to, the following:
1. Any advertisement, article, notice or other communication published in any newspaper, magazine, or similar media or broadcast over television or radio; and
2. Any seminar or meeting whose attendees have been invited by any general solicitation or general advertising;
Provided, however, that publication by an issuer of a notice in accordance with Rule 230.135c or filing with the Commission by an issuer of a notice of sales on Form D (17 CFR 239.500) in which the issuer has made a good faith and reasonable attempt to comply with the requirements of such form, shall not be deemed to constitute general solicitation or general advertising for purposes of this section; Provided further, that, if the requirements of Rule 230.135e are satisfied, providing any journalist with access to press conferences held outside of the United States, to meetings with issuer or selling security holder representatives conducted outside of the United States, or to written press-related materials released outside the United States, at or in which a present or proposed offering of securities is discussed, will not be deemed to constitute general solicitation or general advertising for purposes of this section.
Please also see the embedded document.