我正在使用mailkit从邮箱中获取电子邮件并将其保存到数据库中以显示在我的MVC应用程序中。
我将html电子邮件保存为数据库中的纯文本，我可以获取附件并将其保存在文件系统中，但是当电子邮件中有inline图像时，我会出现问题，因为签名和其他空白映像也被保存为附件在文件系统中。
有没有办法区分内联附件和签名或其他空白图像？
预先感谢
您使用哪个IMAP库无关需要使用一些创造力来解决。
您可以做的是从FAQ中的HtmlPreviewVisitor示例开始，并将其修改为每一个so Lightsly，以将附件拆分为2个列表：
- 实际附件列表
- html引用的图像列表实际（通过行走HTML并跟踪哪些图像被引用）
代码：
/// <summary>
/// Visits a MimeMessage and splits attachments into those that are
/// referenced by the HTML body vs regular attachments.
/// </summary>
class AttachmentVisitor : MimeVisitor
{
List<MultipartRelated> stack = new List<MultipartRelated> ();
List<MimeEntity> attachments = new List<MimeEntity> ();
List<MimePart> embedded = new List<MimePart> ();
bool foundBody;
/// <summary>
/// Creates a new AttachmentVisitor.
/// </summary>
public AttachmentVisitor ()
{
}
/// <summary>
/// The list of attachments that were in the MimeMessage.
/// </summary>
public IList<MimeEntity> Attachments {
get { return attachments; }
}
/// <summary>
/// The list of embedded images that were in the MimeMessage.
/// </summary>
public IList<MimePart> EmbeddedImages {
get { return embedded; }
}
protected override void VisitMultipartAlternative (MultipartAlternative alternative)
{
// walk the multipart/alternative children backwards from greatest level of faithfulness to the least faithful
for (int i = alternative.Count - 1; i >= 0 && !foundBody; i--)
alternative[i].Accept (this);
}
protected override void VisitMultipartRelated (MultipartRelated related)
{
var root = related.Root;
// push this multipart/related onto our stack
stack.Add (related);
// visit the root document
root.Accept (this);
// pop this multipart/related off our stack
stack.RemoveAt (stack.Count - 1);
}
// look up the image based on the img src url within our multipart/related stack
bool TryGetImage (string url, out MimePart image)
{
UriKind kind;
int index;
Uri uri;
if (Uri.IsWellFormedUriString (url, UriKind.Absolute))
kind = UriKind.Absolute;
else if (Uri.IsWellFormedUriString (url, UriKind.Relative))
kind = UriKind.Relative;
else
kind = UriKind.RelativeOrAbsolute;
try {
uri = new Uri (url, kind);
} catch {
image = null;
return false;
}
for (int i = stack.Count - 1; i >= 0; i--) {
if ((index = stack[i].IndexOf (uri)) == -1)
continue;
image = stack[i][index] as MimePart;
return image != null;
}
image = null;
return false;
}
// called when an HTML tag is encountered
void HtmlTagCallback (HtmlTagContext ctx, HtmlWriter htmlWriter)
{
if (ctx.TagId == HtmlTagId.Image && !ctx.IsEndTag && stack.Count > 0) {
// search for the src= attribute
foreach (var attribute in ctx.Attributes) {
if (attribute.Id == HtmlAttributeId.Src) {
MimePart image;
if (!TryGetImage (attribute.Value, out image))
continue;
if (!embedded.Contains (image))
embedded.Add (image);
}
}
}
}
protected override void VisitTextPart (TextPart entity)
{
TextConverter converter;
if (foundBody) {
// since we've already found the body, treat this as an
// attachment
attachments.Add (entity);
return;
}
if (entity.IsHtml) {
converter = new HtmlToHtml {
HtmlTagCallback = HtmlTagCallback
};
converter.Convert (entity.Text);
}
foundBody = true;
}
protected override void VisitTnefPart (TnefPart entity)
{
// extract any attachments in the MS-TNEF part
attachments.AddRange (entity.ExtractAttachments ());
}
protected override void VisitMessagePart (MessagePart entity)
{
// treat message/rfc822 parts as attachments
attachments.Add (entity);
}
protected override void VisitMimePart (MimePart entity)
{
// realistically, if we've gotten this far, then we can treat
// this as an attachment even if the IsAttachment property is
// false.
attachments.Add (entity);
}
}
使用它：
var visitor = new AttachmentVisitor ();
message.Accept (visitor);
// Now you can use visitor.Attachments and visitor.EmbeddedImages
更简单，尽管更少的错误（正弦它实际上并未验证HTML引用的图像），但这样做的方法是：
var embeddedImages = message.BodyParts.OfType<MimePart> ().
Where (x => x.ContentType.IsMimeType ("image", "*") &&
x.ContentDisposition != null &&
x.ContentDisposition.Disposition.Equals ("inline" StringComparison.OrdinalIgnoreCase));
现在您有了embeddedImages的列表，您必须找出一种方法来确定它们是仅在签名中使用还是在HTML中使用的其他地方。
很可能还必须分析HTML本身。
也可能值得注意的是，某些HTML邮件将引用位于邮件中 not 的网络上的图像。如果您也需要这些图像，如果我提供的代码无法将其定位在消息的哑剧中，则需要修改TryGetImage从Web下载图像。
对于文本/普通消息（根本无法使用图像），将签名与消息主体的其余部分分开的通用约定是只有2个破折号和一个空间的线：--。
从我对具有签名的HTML消息的有限经验来看，它们似乎并未遵循类似的约定。查看我使用Outlook从Microsoft上收到的一些HTML消息，它们在消息结束时似乎在<table>之内。但是，这假定该消息不是答复。一旦您开始解析消息回复，此<table>最终出现在消息的中间，因为要回复的原始消息在最后。
由于每个人的签名也不同，我不确定这种<table>是否是Outlook惯例，或者人们是否正在手动构建他们的签名，而他们都只是在使用桌子（我也只看到一个桌子）很少有，大多数不使用签名，所以我的样本量很小）。
使用https://mailsystem.codeplex.com/：
班级阅读电子邮件：
class readMail:IDisposable
{
public Imap4Client client = new Imap4Client();
public readMail(string mailServer, int port, bool ssl, string login, string password)
{
Pop3Client pop = new Pop3Client();
if (ssl)
{
client.ConnectSsl(mailServer, port);
}
else
client.Connect(mailServer, port);
client.Login(login, password);
}
public IEnumerable<Message> GetAllMails(string mailBox)
{
IEnumerable<Message> ms = GetMails(mailBox, "ALL").Cast<Message>();
return GetMails(mailBox, "ALL").Cast<Message>();
}
protected Imap4Client Client
{
get { return client ?? (client = new Imap4Client()); }
}
private MessageCollection GetMails(string mailBox, string searchPhrase)
{
try
{
MessageCollection messages = new MessageCollection();
Mailbox mails = new Mailbox();
mails = Client.SelectMailbox(mailBox);
messages = mails.SearchParse(searchPhrase);
return messages;
}
catch(Exception ecc)
{
}
}
public void Dispose()
{
throw new NotImplementedException();
}
}
，然后：
using (readMail read = new readMail("host.name.information", port, true, username, password) )
{
var emailList = read.GetAllMails(this.folderEmail);
int k = 0;
Mailbox bbb = read.client.SelectMailbox(this.folderEmail);
int[] unseen = bbb.Search("UNSEEN");
foreach (Message email in emailList)
{
/// Contains all parts for which no Content-Disposition header was found. Disposition is left to the final agent.
MimePartCollection im1= email.UnknownDispositionMimeParts;
//Collection containing embedded MIME parts of the message (included text parts)
EmbeddedObjectCollection im2 = email.EmbeddedObjects;
//Collection containing attachments of the message.
AttachmentCollection attach=email.Attachments;
}
}
就我而言，所有签名的图像都在未知的示例示例中，但这可能是一个特定的情况（不同的电子邮件客户端等）。因此，对于我所知道的，我没有找到任何库将嵌入图像与上下文图像分开的库签名图像