Parsing the date from the header stream of an .msg file - c++

Question

I'm trying to obtain the send date of an .msg email message file. After endless searching, I've concluded that the send date is not kept in its own stream within the file (but please correct me if I'm wrong). Instead, it appears that the date must be obtained from the stream containing the standard email headers (a stream named __substg1.0_007D001F).
So I've managed to obtain the email header stream and store it in a buffer. At this point, I need to find and parse the Date field from the headers. I'm finding this difficult, because I don't believe I can use a standard email-parsing C++ library. After all, I only have a header stream--not an entire, standard email file.
I'm currently trying a regex, perhaps something like this:
std::wregex regexDate(L"^Date:(.*)\r\n");
std::wsmatch match;
if (std::regex_search(strHeader, match, regexDate)) {
//...
}
But I'm reluctant to use regex (I'm concerned that it'll be error-prone), and I'm wondering if there's a more robust, accepted approach to parsing headers. Perhaps splitting the header string on new lines and finding the one that begins with Date:? Any guidance would be greatly appreciated.
One other consideration: I'm not sure it's possible to read in the header stream line by line, because IStream doesn't have a get line method.
(Side note: I've also tried obtaining message data using C++ Outlook automation, but that seems to involve some security and compatibility issues, so it won't work out.)

Answer 1

The Send Date is stored in an msg file, but as you note, it is not in its own stream. As a short, fixed-width value, it can be found in the __properties_version1.0 stream object under the root entry (or under an attachment object for embedded messages), with the property ID 0x00390040, the PidTagClientSubmitTime Property, which is described in the MS-OXOMSG documentation as
Contains the current time, in UTC, when the email message is submitted.
MS-OXCMAIL Section 2.2.3.2.2: Sent time elaborates on this:
To set the value of the PidTagClientSubmitTime property ([MS-OXOMSG] section 2.2.3.11), clients MUST set the Date header value, as specified in [RFC2822].
This has the property type 0x0040, pTypTime, which, per the list of Property Data Types:
8 bytes; a 64-bit integer representing the number of 100-nanosecond intervals since January 1, 1601