Lately, with my new iPhone 6, I’ve been unable to reply to certain messages because I receive an error message similar to the subject line. Other messages seem to go OK. It’s a Verizon phone. I talked to Verizon sales people in the local dealership franchise, and they said it was a problem with Dreamhost. One young woman suggested it might be the protocol(s) used by the iPhone, but others there denied that as a possibility. Who can tell me how to fix this problem. One of the messages I wanted to respond to had a gmail.com address. It was from a former co-worker that I hadn’t seen in thirty or more years, inquiring if I was the same guy that he knew back then. Of course I wanted to respond!
It sounds like you don’t have your mail configured correctly. Hard to say since you didn’t tell us how you set it. With “mail relay” in the error message it sounds like your SMTP or outgoing server is using a non-dreamhost server (most likely verisons, but that’s just a guess)
“does not support relays” means that you are attempting to send outbound SMTP traffic to a mail system that is not set up to accept your connection. It probably means that you are not sending the logon credentials and your iPhone is configured to not have a user name and password sent as part of the security.
(Back in the early days in the internet, some 30+ years ago, all mailers would simply do the relay operation. If the message was not for their site they would simply pass it along to where it was intended to go. That was before “SPAM” was discovered, much to the dismay of the Hormel Foods Corporation.)
Instructions on how to properly configure an iPhone with Email at DreamHost are in the wiki at the URL
If you follow it (changing the names where appropriate in the example to your real domain name) then you should not have a problem.