Launch default email client to open a “send email” window with a pre-selected file attachment

问题

I need to add a "Create and email" feauture to our app. Our program creates an output file, and I must then launch the default email client to open a "write email" window, and with the output file preselected as an attachment.

I've seen other programs do it, even if the default client is Thunderbird instead of Outlook.

回答1:

I ended up using MAPI to achieve it. I used LoadLibrary and GetProcAddress to get the needed functions.

The code I used is this:

bool MailSender::Send(HWND hWndParent, LPCTSTR szSubject)
{
    if (!m_hLib)
        return false;

    LPMAPISENDMAIL SendMail;
    SendMail = (LPMAPISENDMAIL) GetProcAddress(m_hLib, "MAPISendMail");

    if (!SendMail)
        return false;

    vector<MapiFileDesc> filedesc;
    for (std::vector<attachment>::const_iterator ii = m_Files.begin(); ii!=m_Files.end(); ii++)
    {
        MapiFileDesc fileDesc;
        ZeroMemory(&fileDesc, sizeof(fileDesc));
        fileDesc.nPosition = (ULONG)-1;
        fileDesc.lpszPathName = (LPSTR) ii->path.c_str();
        fileDesc.lpszFileName = (LPSTR) ii->name.c_str();
        filedesc.push_back(fileDesc);
    }

    std::string subject;
    if (szSubject)
        subject = utf16to8(szSubject).c_str();
    else
    {
        for (std::vector<attachment>::const_iterator ii = m_Files.begin(); ii!=m_Files.end(); ii++)
        {
            subject += ii->name.c_str();
            if (ii+1 != m_Files.end())
                subject += ", ";
        }
    }

    MapiMessage message;
    ZeroMemory(&message, sizeof(message));
    message.lpszSubject = (LPSTR) subject.c_str();
    message.nFileCount = filedesc.size();
    message.lpFiles = &filedesc[0];

    int nError = SendMail(0, (ULONG)hWndParent, &message, MAPI_LOGON_UI|MAPI_DIALOG, 0);

    if (nError != SUCCESS_SUCCESS && nError != MAPI_USER_ABORT && nError != MAPI_E_LOGIN_FAILURE)
        return false;

    return true;
}

回答2:

Using the mailto scheme may be a solution but it's going to be tricky due to restrictions on what fields are considered safe (see the RFC 2368 and 6067 for the full details if you want to go that route).

Another solution would be to figure out what email client is installed and - wherever possible - launch it and specify all you need via command line. See here for Thunderbird & here for Outlook.