how to forward item if it is moved ?

[Izulle]

Well it might be SO-lije question but I decided to try here first.
My colleage added variant of create_item for forwarding messages - it adds Forwardtem into request.
If you interested I can put his code here.
It works fine but I have problems with very specific scenario.
I am turn off wifi on my device, select letter and forward it. Internet is off so command cannot be perfomed so I keep it for future next try. Meanwhile I open another client on another device and move letter which I wanted to forward, into another folder. Then I turn on wifi on first device and try to forward message once more.

Here I have a choice as a coder - to run delayed commands before syncrhonizing with server or after synchronizing. I am run commands first. My create_item with ForwardItem cannot be fulfilled cause letter is moved and item with given ItemId dont exists any more.

Should I run syncronization first, I am still dunno how to find new itemId of forwarded message.
I am using SyncFolderItems for syncroniztion so I can see that message is deleted from old folder and new message is created in another. But how can I be sure that this is the same message ... I cannot. I just can to delete my forward command cause I see that item I wanted to forward not exist any more.

    item_id create_item_impl(const message& the_message, const std::string& fw_message)
    {
        the_message.get_to_recipients();
        std::stringstream sstr;
        sstr << "<m:CreateItem MessageDisposition=\"SendAndSaveCopy\">";
        sstr << "<m:Items>"
        << "<t:ForwardItem>";

        sstr << the_message.get_body().to_xml();

        sstr << "<t:ToRecipients>";
        for (auto& r: the_message.get_to_recipients()) {
            sstr << r.to_xml();
        }
        sstr << "</t:ToRecipients>";

        auto cc = the_message.get_cc_recipients();
        if (cc.size()) {
            sstr << "<t:CcRecipients>";
            for (auto& r: cc) {
                sstr << r.to_xml();
            }
            sstr << "</t:CcRecipients>";
        }

        auto bcc = the_message.get_bcc_recipients();
        if (bcc.size()) {
            sstr << "<t:BccRecipients>";
            for (auto& r: bcc) {
                sstr << r.to_xml();
            }
            sstr << "</t:BccRecipients>";
        }

        sstr << "<t:ReferenceItemId Id=\""
        << the_message.get_item_id().id()
        << "\" ChangeKey=\""
        << the_message.get_item_id().change_key()
        << "\" />";

        sstr << "</t:ForwardItem>"
        << "</m:Items>"
        << "</m:CreateItem>";

        auto response = request(sstr.str());

        const auto response_message =
        internal::create_item_response_message::parse(std::move(response));
        if (!response_message.success())
        {
            throw exchange_error(response_message.result());
        }

        return item_id();
    }

[SebastianBecker2]

What you can do to track mails through moves, is to define user defined properties for the mails.
I haven't done it with the library. But EWS allows you to define your own properties. All you would have to do is to create a GUID and add that as a property to the mail item. This way you can track the item no matter where it is.
At least according to this stack exchange answer
But it seems to have downsides to. I would assume a copy of a mail can lead to confusion.

The answer also mentions the PidLidGlobalObjectId. But afaik this only exists for calendar items.
This is actually something I use. But the PidLidCleanGlobalObjectId instead. The PidLidGlobalObjectId changes when the start date/time or end date/time is changed, as far as I remember. I needed an ID that remained constant regardless of changes to the item.

If you find a better solution to ID a mail item even through moves to other folders, please let me know. That might be something I have to face sooner or later myself. For now, I treat a move of an mail item just like a delete of the old and a create in the new location.

Hope this helps.