I am having a problem receiving emails from certain clients. We do not believe the problem is on our server but would like to do a workaround for this client. Anyways the error log that was give on their server is
"503 5.5.1 Error: send HELO/EHLO first"
I do not want to set smtpd_helo_required to "no" to all incoming domains.
Is there anyway I can filter the client's ip to allow them to email us without globally changing the configuration like a network filter of some sort?
Thanks in advance