> On 4 Feb 2025, at 01:22, Theo de Raadt <deraadt@openbsd.org> wrote:
> 
> What is the point of this 'validation'?
> 
> If the environment variable is trash, the mail doesn't work.

To prevent silent e-mail loss. The "sendmail: command failed: 501
5.1.3 Recipient address syntax error" in the syslog looks not
correlating with calendar(1) to me.

Anyway, my question is not requirement, right?