[exim] How to reject overlong addresses/local parts in From:…

Hello,

occasionally exim logs in paniclog failing rewrite rules:

2020-12-11 17:14:47 1knl4B-0002o8-Eu no @ found in the subject of an
address list match:
subject="ppppppppppppppkkkkkkkkkkkkkkkkkttttttttttttttttttttttttrrrrrrrrrrrrrrrrrrrrrrrrssssssssssssssssssssssssssaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaadddddddddddddddddfffffffffffffffffffffcccccccccccccccbbbbbbbbbbbbbbbbbbbbbbbbbbb"
pattern="*@tuced.eu"

The rewrite rule is
*@tuced.eu                $local_part@???

It comes from an e-mail with an overlong From: header:
From: "…"
<PPPPPPPPPPPPPPKKKKKKKKKKKKKKKKKTTTTTTTTTTTTTTTTTTTTTTTTRRRRRRRRRRRRRRRRRRRRRRRRSSSSSSSSSSSSSSSSSSSSSSSSSSAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAADDDDDDDDDDDDDDDDDFFFFFFFFFFFFFFFFFFFFFCCCCCCCCCCCCCCCBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB@…>

I'd like to reject such "address monsters". How's the best way to
achieve this?

Thanks in advance,
Frank

--
Frank Richter
URZ, TU Chemnitz, Germany