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Opera Mail qualifies two nearby identical mails as duplicate

  • Opera Mail qualifies two nearby identical mails as duplicate
    Two very similar mails have been downloaded from server.
    The only difference (if to examine its body and the normal header) are the recipient email address and the mail time stamp (receive date).
    Bodies are identical.
    Both mails are stored in one mailbox/account.
    These two mails are listed in mail list view only if to enable "Show duplicates".
    Actually these mails should not be classified as duplicates.
    Why does Opera Mail do it? Is it maybe a known bug?

  • Duplicates is defined by having the same message ID, not by the content - I think. Not working for Opera I can't be completely certain, but that is how they should define it. If the message ID headers are the same, they should be the same message (though perhaps sent through different servers).

  • Yes, it's by the Message-ID header value (as long as the header's value is proper syntax where it isn't ignored by Opera). The body content doesn't even have to be the same.

    Doing things this way is fine as the header value should be unique to its message. No need to do an SHA-256 sum of the messages and compare for example.

    There's nothing wrong with having more advanced options for duplicate handling though. Opera Mail jst doesn't have any.