How to troubleshoot error messages experienced when sending and receiving email

Email > Troubleshooting email problems and errors
This article is based on this Microsoft Knowledge Base article, "How to troubleshoot error messages that you receive when try to send and receive e-mail in Outlook and in Outlook Express." This article has information specific to and links to help you troubleshoot email issues.

You may have experienced one of the following error messages when attempting to send or receive email:
  • No connection could be made because the target machine actively refused it.
  • The server could not be found. (Account:account name, POPserver:'mail', Error Number: 0x800ccc0d)
  • Server Response: '+OK 752 octets follow.', Port: 110, Secure(SSL): No
  • Task 'server name - Sending and Receiving' reported error (0x800ccc0f): 'The connection to the server was interrupted. If this problem continues, contact your server administrator or Internet service provider (ISP).
  • Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity. Account. account name, Server: 'server name', Protocol: POP3, Server Response: '+OK', Port: 110, Secure(SSL): No, Error Number: 0x800ccc0f
  • Task 'SMTP server name - Sending and Receiving' reported error (0x80042109): 'Outlook is unable to connect to your outgoing (SMTP) e-mail server. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).'
  • The operation timed out waiting for a response from the receiving (POP) server 0x8004210a
  • A time-out occurred while communicating with the server 0x800ccc19
You may also receive an error message that includes one or more of the following error codes:


Below are some of the methods used to remedy email sending and receiving errors.

Method 1: Confirm that your e-mail server settings are correct

This applies to all email programs, not just Outlook. If you use Outlook, Eudora, Mozilla Thunderbird or any other email program, ensure that the POP and SMTP server settings are correct.

To check individual email account login information log in to SmarterMail as postmaster (or any other user who has Domain Administrator permissions) and go to "Domain Settings >> Email Users."

To confirm that the username password are working correctly, log into webmail using the username/password for the account in question.

If you can log into webmail, check the POP3 Server and SMTP Server settings in your email program. Knowledge Base articles detailing how to check or change these settings for some popular email program are here.

Method 2: Examine the configuration of your firewall software

In order to test this you will have to temporarily bypass your local firewall software (Norton, McAfee, ZoneAlarm, etc.) or hardware firewall (Linksys, Netgear, or other router, network device provided by your ISP, etc.). Consult your ISP, hardware or software manufacturer's documentation for instructions related to temporarily bypassing the firewall.

Method 3: Check your antivirus vendor's Web site for additional suggestions

Antivirus software is a common cause of email connection problems. If you changed the SMTP server settings in Outlook the antivirus software may not have detected the change, or is blocking the traffic or port for some other reason. This Microsoft Knowledge Base article includes links to most antivirus software vendors support or troubleshooting pages.

Method 4: Determine whether your modem is functioning correctly

If you are using a modem and can access the internet this is not a likely cause of email problems. If you are using a broadband/cable/DSL connection, you can rule it out as a source of email errors.

Note however, that many ISPs block port 25 for outgoing mail. So we also provide outgoing mail service on port 8889. If you have ruled out anti-virus or firewall interference, try changing your SMTP setting from port 25 to 8889.

Method 5: Verify the Maximum Transmission Unit (MTU) size that is set on your router

We have found this to be a frequent cause of email errors in the past. Read the relevant section of the Microsoft article to determine whether this may apply to your home configuration.

Method 6: Remove and reinstall Outlook Express

Outlook Express can also be a frequent source of email errors, and removing and reinstalling the program can resolve them. Outlook and outlook express are prone to corruption of their configuration, sometimes just in the process of changing settings. If the above methods do not resolve your problems, or are not applicable, please remove and reinstall Outlook Express.

Method 7: Create a new e-mail profile

In most cases the prior steps lead to a resolution. But if they do not, try creating a new e-mail profile. The Microsoft article has links to articles detailing methods to create a new profile.

Method 8: Delete suspicious messages from your mailbox

Many times an email message with a malformed or otherwise damaged header can cause mail downloads to stall or fail completely. If you suspect this may be the case, log in to your email account using webmail and delete any spam or suspicious messages.

Method 9: Verify that all SMTP e-mail addresses in a distribution list are valid

If you are sending mail to a large number of recipients, an invalid address in the list can cause an error. Check your recipient list for obviously invalid addresses. If none are found, try breaking your list into smaller sections, in an attempt to locate the invalid address.