| Event Id | 4001 |
| Source | MSExchangeTransport |
| Description | Message delivery to the remote domain mail.example.com failed. The error message is An SMTP protocol error occurred. , RCPT, 554 Service unavailable; [ip address] blocked using dialups.mail-abuse.org. Data: 0000: d7 02 04 c0 |
| Event Information | Following document will give more information about this event. |
| Reference Links | How
to troubleshoot the "504 need to authenticate first" SMTP protocol
error Cannot send e-mail messages to a growing list of domains |
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