[Exim] How to restrict long header lines?

Hi,

We are using Exim 4.10 under Solaris with no difficulties.

We have a web-mail client that seems to have problems handling
individual header lines that are greater than 4096 characters in
length.

Exim 4.10 apparantely lets you set the maximum size of ALL the headers
combined, but I didn't see a way to set a limit on the size of an
individual header line itself. I don't want to set HEADER_MAXSIZE to
4096 as that would be too low for the aggregate of all headers.

Is there any way to put a limit on individual header-line length,
either in the config file or in a system-filter file?

Thanks,

Dean Brooks
dean@???