internal abstract void RemoveRecipient(RecipientType recipientType, ref object cachedHeader, EmailRecipient oldRecipient);
internal abstract void AddRecipient(RecipientType recipientType, ref object cachedHeader, EmailRecipient newRecipient);
internal abstract void RemoveRecipient(RecipientType recipientType, ref object cachedHeader, EmailRecipient oldRecipient);
internal abstract void AddRecipient(RecipientType recipientType, ref object cachedHeader, EmailRecipient newRecipient);