indicate email has attachment in summary buffer

[Leon]

Dear all,

I have just completed a project with 4 people based on emails. I
almost missed an important file attached in an email. That's how I
found an indicator of attachment in gnus summary line will be
practically useful.

It happened like this.
The message, as we always include the original, became very long. And
the attachment in gnus is shown at the end of the article buffer that
I missed it.

So I'm wondering is there any way I can have an indicator in the
summary line for emails that have attachment. For example something
like this will be useful:

O +|31-Jul| Hadron Quark    | 160|@● Always show 20 posts

The '@' at the beginning of the subject indicates attachment.

Thank you!
-- 
Leon