How can I detect that an email has been rejected as spam by the recipient?

Is there a way to 开发者_JAVA技巧check if a sent e-mail has been marked as spam or deleted?

I work with Rails 3.

No, there isn't. After your mail has been sent to your receiver's SMTP server, there's no way to track it down anymore.

I know what you're thinking: how can some mail-clients track down wether an email has been read or not (e.g. in Outlook). They can do this by adding a little img-tag to their mails (html). When a user opens the mail, it'll open the path specified in the img's src-attribute. Since that's a script (like PHP or something), it can automatically sets a flag to 'seen' when a mail has been opened.

Of course, there are some other ways to track this down, but I think this is the most popular one.

However, this can't be done to check whether a mail has been rejected, deleted or moved to the spam-folder.