Can an HTML email body reference a file sent as an attachment (in the same email)?

问题

Can an HTML email use an image attachment as the source for tag?

Let's say I am sending an email with per-email specific images - and they are sent as an attachment to the email - can the HTML body within the email use the those images? My guess would be no, but are there any hacks or workarounds that would make it work?

Thanks,

回答1:

No hacks needed. Use the cid: URI scheme

 --boundary-example 1
 Content-Type: Text/HTML; charset=US-ASCII

 to the other body part, for example through a statement such as:
 <IMG SRC="cid:foo4*foo1@bar.net" ALT="IETF logo">

 --boundary-example-1

 Content-ID: <foo4*foo1@bar.net>
 Content-Type: IMAGE/GIF
 Content-Transfer-Encoding: BASE64

 R0lGODlhGAGgAPEAAP/////ZRaCgoAAAACH+PUNvcHlyaWdodCAoQykgMTk5
 NSBJRVRGLiBVbmF1dGhvcml6ZWQgZHVwbGljYXRpb24gcHJvaGliaXRlZC4A
 etc...

 --boundary-example-1--

来源：https://stackoverflow.com/questions/9983248/can-an-html-email-body-reference-a-file-sent-as-an-attachment-in-the-same-email