I have been using greylisting on our server for about a month now. One issue that just occurred today is that mail I'm sending to other accounts on our system are being greylisted despite having sent email successfully up until now. For instance, I have sent an email from my account to a client's email address and received a Greylisting warning, when it worked this morning. I am sending messages using our mail server, through my Comcast Internet service (i.e. my email client is sending through my smtp server, not via Comcast).
The "record expiration" setting for our server is 90 days - so that shouldn't be an issue.
Why would my own email suddenly be greylisted when it's already, recently, been "approved"? I am nervous this is happening to other incoming email (I have not check the logs yet). It's one thing to have incoming email delayed periodically for the greylisting check; however, if this happens too often my clients will begin screaming.
Any ideas or advice? Thanks.