The plugin doesn’t save the value of the “use gravatar” checkbox for comments by registered users (see below), trackbacks/pingbacks (there is no e‑mail address) and comments that are marked as spam when they are saved. If you mark a comment as spam later, the table entry is not removed, since the same e‑mail address might also be used by non-spam comments. If a comment is marked as spam by Akismet or similar plugins and you later manually mark it as non-spam, what the user selected when submitting the comment will already be lost. This only happens with spam comments, not comments who just need to be moderated, e.g. because of the ‘needs at least one published comment’ rule.
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