Description:
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The imap_fetchheader function could have FT_PREFETCHTEXT option to return the raw message headers. It could be usefull if you have to parse headers like Message-Context or Content-Class which are not returned with a function like imap_fetch_overview.
The problem is that when I set the FT_PREFETCHTEXT option, my message is flagged to Seen (readed mail), so it's pretty annoying. When I remove this option flag, everything's fine.

Reproduce code:
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$this->mbox = imap_open("{127.0.0.1/imap/novalidate-cert/notls/norsh}INBOX", "login", "password");

$raw_headers = imap_fetchheader($this->mbox, 1, FT_PREFETCHTEXT|FT_UID);

Expected result:
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I just want to retrieve all of the headers. And I didn't want to change the read status of my message.
If I set "FT_UID" instead of "FT_PREFETCHTEXT|FT_UID", my message is not marked as read but I couldn't get all the headers.

Actual result:
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Actually, my message is marked as read (Seen flag).