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The posts are at medium quality. Also it is since that the previous owner can't provide a signature for me and I can only sign the profile address.
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Signing a message from a profile address means nothing. Basic idea of signing is to prove the ownership.
If you bought recently and got no BTC address from unedited post , I think you should wait 3 months after posting a BTC address that you can sign. Otherwise, you cannot prove the ownership of it and it would be just gambling buying your Sr member account.