Way back when - there was a "best practice" by some and talk of a requirement of putting "ADV" in a subject line to denote "advertisement" but I don't believe that ever got a lot of traction. A "do not email" like the "do not call list" is the same.
Email spam filters are also better than they were "way back when".
I would recommend keeping some good records for fair lending and CRA of your solicitations, ie. who, where, any prescreening techniques employed, etc.
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AndyZ CRCM
My opinions are not necessarily my employers.
R+R-R=R+R
Rules and Regs minus Relationships equals Resentment and Rebellion. John Maxwell