I am facing a strange problem. I have configured some users to use their mail box from their mobile devices and outlook using POP3 and SMTP connection. The problem is that they can receive emails but they are not able to send emails. Whenever they send an email it goes to Outbox with a message status "Failed". This problem occurs with only some users others are able to send and receive perfectly without any error.

We have domain, Windows Server 2008 and Exchange Server 2010.

I have tried by changing the ports an security layers but no success.

Please help guys...

  • Are you using port 587 to send mail? If you are using port 25, don't, because that is routinely blocked especially for roaming users. If you are using 587, do you have any logs on the server? – Law29 Jan 17 '16 at 18:00
  • We have port forwarding so, we are using another ports. Logs means log of any send attempt log by user? Can you suggest me where can i find this log on server? – Dhaval Vadher Jan 20 '16 at 5:41

Why are you using Outlook and mobile devices with POP3/SMTP? Outlook should be using Outlook Anywhere for remote connection and mobile devices using ActiveSync. That will avoid problems with sending email through some of the most heavily scanned and blocked ports. With POP3 you will lose email, it is just a matter of when.

  • We need to handle them separately without removing the mails from server. Therefore using this connectivity type a local mail copy will only be affected and the copy on server will remain saved. Another thing is, I guess Outlook Anywhere and ActiveSync will require exchange server name to be hosted on web, because it will work Connect Exchange over HTTP, but we are connecting through IP address. Outlook Anywhere and ActiveSync will require strong internet connectivity which is not possible in every remote location where the user will try to access their mail. Please correct me if I am wrong. – Dhaval Vadher Jan 20 '16 at 5:35
  • If you are connecting via IP address, then switch to a DNS entry. Even if the IP address is dynamic it is still possible to use a host name with a dynamic DNS service. Both Outlook Anywhere and ActiveSync are designed for use on the move, so can work on pretty any kind of internet connection. They can work offline completely and then process email sent when a connection is made. ActiveSync is also more battery efficient than POP on a mobile device, because of the way it works. Furthermore, it is much easier to lose content with POP then ActiveSync/Outlook Anywhere. – Sembee Jan 20 '16 at 15:32
  • While POP can be configured to hold the data, it is very easy for it to be misconfigured and remove the content from Exchange. If you want to keep control of the email, then block the use of POP/IMAP for clients and have them use the native clients. With a modern Exchange server implementation, your arguments for using POP are no longer valid. – Sembee Jan 20 '16 at 15:34
  • Okay Sembee, thanks for the information. We are only using IP connection not hosted DNS. I have to take a look and learn on changing the connectivity type and that may take longer time. But at present time what is the alternate way that i can allow users to send mails and solve the problem. In other words if I ask, is there any possibility that the user was restricted to send mail through POP/SMTP in past, which is restricting now? In user properties I have POP3, IMAP and MAPI are enabled. – Dhaval Vadher Jan 22 '16 at 9:59
  • DNS doesn't matter. You get a static IP address from your ISP, then just crate the DNS entry wherever your domain is located. The ISP/hosted DNS service doesn't require anything more. As already pointed out, the most likely cause is blocking of the port. Changing to use something other than SMTP, or switching to a VPN will provide a more reliable experience. – Sembee Jan 22 '16 at 13:53

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