如何获取电子邮件附件元数据而不是来自 Gmail 的内容？

Question

我只需要 header 和 Gmail 附件的元数据，我不想收到电子邮件 body 或附件的内容，因为它们可能非常大而且我不不需要他们。

有没有办法通过 AE.Net.Mail 或 gmail api 做到这一点？它似乎只有 headers 的一个选项，它不会为我获取附件元数据。

MailMessage[] GetMessages(string startUID, string endUID, bool headersonly = true, bool setseen = false);

Answer 1

最终，我放弃了 AE.Net.Mail，转而使用 Gmail API。而且我能够从消息获取请求中获取附件元数据，而无需获取实际的附件文件。

https://developers.google.com/gmail/api/v1/reference/users/messages/get

Answer 2

如果您使用MailKit而不是AE.Net.Mail，您可以使用以下代码片段获取附件的元数据：

using (var client = new ImapClient ()) {
    client.Connect ("imap.gmail.com", 993, true);
    client.Authenticate ("username", "password");

    client.Inbox.Open (FolderAccess.ReadWrite);

    var summaries = client.Fetch (0, -1, MessageSummaryItems.UniqueId |
        MessageSummaryItems.BodyStructure | // metadata for mime parts
        MessageSummaryItems.Envelope);      // metadata for messages

    foreach (var summary in summaries) {
        // Each summary item will have the UniqueId, Body and Envelope properties
        // filled in (since that's what we asked for).
        var uid = summary.UniqueId.Value;

        Console.WriteLine ("The UID of the message is: {0}", uid);
        Console.WriteLine ("The Message-Id is: {0}", summary.Envelope.MessageId);
        Console.WriteLine ("The Subject is: {0}", summary.Envelope.Subject);
        // Note: there are many more properties, but you get the idea...

        // Since you want to know the metadata for each attachment, you can
        // now walk the MIME structure via the Body property and get
        // whatever details you want to get about each MIME part.
        var multipart = summary.Body as BodyPartMultipart;
        if (multipart != null) {
            foreach (var part in multipart.BodyParts) {
                var basic = part as BodyPartBasic;

                if (basic != null && basic.IsAttachment) {
                    // See http://www.mimekit.net/docs/html/Properties_T_MailKit_BodyPartBasic.htm
                    // for more details on what properties are available.
                    Console.WriteLine ("The size of this attachment is: {0} bytes", basic.Octets);
                    Console.WriteLine ("The file name is: {0}", basic.FileName);

                    // If you want to download just this attachment, you can download it like this:
                    var attachment = client.Inbox.GetBodyPart (uid, basic);
                }
            }
        }
    }

    client.Disconnect (true);
}

请记住，由于 MIME 是树结构而不是平面列表，因此您实际上希望递归地遍历多个部分。

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