Our SBS 2003 Exchange Server is intermittently not receiving external emails. I've run a few incoming tests using https://www.testexchangeconnectivity.com and quite frequently the test fails with the following message: Attempting to send a test e-mail message to xxx@xxx.com using MX xxx.xxx.com. (I've removed the email add & MX server) Delivery of the test message failed. Additional Details The server returned status code -1 - Failure sending mail. Exception details: Message: Failure sending mail. Type: System.Net.Mail.SmtpException Stack trace: at System.Net.Mail.SmtpClient.Send(MailMessage message) at Microsoft.Exchange.Tools.ExRca.Tests.SmtpMessageTest.PerformTestReally() Exception details: Message: Failure sending mail. Type: System.Net.Mail.SmtpException Stack trace: at System.Net.Mail.SmtpClient.Send(MailMessage message) at Microsoft.Exchange.Tools.ExRca.Tests.SmtpMessageTest.PerformTestReally() Exception details: Message: Failure sending mail. Type: System.Net.Mail.SmtpException Stack trace: at System.Net.Mail.SmtpClient.Send(MailMessage message) at Microsoft.Exchange.Tools.ExRca.Tests.SmtpMessageTest.PerformTestReally() I've also started logging the SMTP Virtual Server and I'm getting (what I think) are some unusual entries: 22:53:11 70.87.105.162 - - 0 22:53:11 70.87.105.162 EHLO - 0 22:53:11 70.87.105.162 - - 0 22:53:11 70.87.105.162 MAIL - 0 22:54:13 70.87.105.162 - - 0 22:54:13 70.87.105.162 EHLO - 0 22:54:13 70.87.105.162 - - 0 22:54:13 70.87.105.162 MAIL - 0 22:54:14 70.87.105.162 - - 0 22:54:14 70.87.105.162 RCPT - 0 22:54:14 70.87.105.162 - - 0 22:54:14 70.87.105.162 DATA - 0 22:54:14 70.87.105.162 - - 0 22:54:15 70.87.105.162 - - 0 22:54:15 70.87.105.162 QUIT - 0 22:54:15 70.87.105.162 - - 0 It's a default installation, there have been no recent changes to the server config, I' not running any email filtering and this issue started occuring about week ago. In most cases we do receive the emails but they might be delayed an hour or so. Any help would be much apprecaited W