::T-Online ::POLIfórum

IP address to check

You are greylisted

EXPLANATION:

T-Online Hungary uses greylisting, which is a technique to reduce the number of incoming unsolicited e-mails (spam). Greylisting refuses your e-mail for the first delivery attempt with a temporary SMTP error, which shouldn't affect successful e-mail delivery, but can cause a slight increase in delivery times.

For more information, you can check greylisting.org.

SOLUTION:

There is nothing to do on your side. If the e-mails from your system suffer unacceptably high delays, configure your mail transfer agent to be more aggressive when resending e-mails in the queue.
It is safe to try to deliver the e-mails waiting in queue 15 minutes after the first attempt.
If you got back a permament delivery error with this message, please contact your mail relay's operator and ask him to set it up correctly. It shouldn't reject your mail permanently when it receives a temporary (4XX) error.