Alan Wylie's Web Site

Fri, 2018-04-27

I started seeing repeated delivery failure messages from the Linux Kernel Mailing list: permalink 

postfix/cleanup[20414]: 2819B22313: info: header Subject: Do You Need A Hand? from vger.kernel.org[209.132.180.67];
opendkim[7694]: too much header data
A quick Google suggested that this was because the header size was greater than the default of 65536 that OpenDKIM accepts. I tried increasing this to 262144, but this didn't help. I then set 
On-Security            accept
in opendkim.conf. This caused the mail to be accepted. I then had a look inside the mail: 
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sego.es; s=default;
<snip>

$ grep DKIM-Signature msg.5SAz | wc -l
1000

$ sed -n '1,/^$/p' msg.6SAz | wc -c
396117
What on earth are sego.es playing at?