A problem with PURLs

My email address was blocked with a bounce from MAILER-DAEMON:

------------------------------------------------------------------
Oggetto: **Message you sent blocked by our bulk email filter**

Uw bericht aan: name@domain.com
is geblokkeerd door onze Spam Firewall. De email die u stuurde met het volgende onderwerp IS NIET BEZORGD:


Your message to: name@domain.,com
was blocked by our Spam Firewall. The email you sent with the following subject has NOT BEEN DELIVERED:

Onderwerp: Subject
---------------------------------------------

This is the answer I received from the mailserver administrator, after a long journey...

> > The message XXX is trying to send has an email or website address in the
> > body of the message that contains "purl[] .org"
> >
> > This string of letters is blocked by our Spam Firewall. As a work around,
> > he can copy the body of the message and send it as a Word attachment.

So I had to cut off from my signature the pointer to my home page PURL. My God!