I am trying to send an email to a recipient with an email address starting with a hyphen/dash, e.g. -firstname.lastname@example.org
The recipient claims the mail address is correct.
postfix/smtpd: warning: Illegal address syntax from ...[...] in RCPT command: <-email@example.com>
I am using Postfix 2.11.3
Any idea how I can send emails to such an address?