Hallo Wolfgang,

Wolfgang Schuster <schuster.wolfgang@googlemail.com> writes:

>>> Oliver Heins wrote:
>>>> Hallo,
>>>>
>>>> I try to send a message from a pdf to a webserver.  This works fine,
>>>> unless the URL has a `#' in it.  Then TeX throws an error:

> Did \letterhash work?

Yes, thank you.  I tried to figure out where \letterhash is defined, but
couldn't find it out grepping through the sources.