SMTP Relay Blocking Error Message When You Send Messages

When you send messages you, may receive an error message that your message cannot be sent because of Simple Mail Transfer Protocol (SMTP) relay blocking. It will be similar to the following error message:
The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was ''. Subject: '', Account: '', Server: '', Protocol: SMTP, Server Response: '550 Relaying Denied', Port: 25, Secure (SSL): No, Server Error: 550, Error Number: 0x800CCC79
OR - the message may say this- *553 sorry, that domain isn't in my list of allowed rcpthosts {#5.7.1}


Outlook Express SMTP Error Fix

Open Outlook Express
Click On Tools
Click On Accounts
Make sure the email account you are having trouble with is highlighted
Click On Properties
Click On Servers Tab
Make sure "my server requires authentication" is enabled
Click Apply then Click OK
NOTE: Double check while you are on the "servers" screen that your incoming mail is: and your outgoing is: or
Also double check that the ACCOUNT name is only the first part of your email address.
Example johnsmith NOT

This information applies to: Outlook

If you are getting an SMTP error please check that the "my server requires authentication" box is checked in your mail settings.

Enabling SMTP Authentication Within Your Mail Client
1. Click Tools
2. Click E-Mail Options
3 .Click View or Change Existing E-Mail Accounts
4. Highlight your account
5. Click Change
6. Click More Settings
7. Click the Outgoing Server tab
8. Check the box My outgoing server (SMTP) requires authentication
9. Click Apply
***NOTE: If you are receiving email through GCT and sending email through another provider you need to set your username
and password up for your email address with your other provider.
EXAMPLE: Your email address with us is but you use a connection with another ISP like SBC or some other DSL connection.
Meaning when you are using your gct email account you are not on a dial up connection to our service.
In Server Settings, Check the box "My Server Requires Authentication"
Click on Setitngs (right next to "My Server Requires Authentication")
Then enter your username and password you have with your other service provider
Click APPLY then go ahead and close the Internet Accounts settings.
ANOTHER NOTE: It is much easier to just use WEBMAIL! Click here for WEBMAIL

This Email information below applies to: MAC
Configure Mail
1. Open Mail.
2. Choose Preferences from the Mail application menu.
If you have not yet set up any accounts, the Mail Setup window appears, and you can skip to Step 7.
3. Click the Accounts icon in the Mail Preferences window.
4. Click Create Account.
5. Choose the correct account type from the pop-up menu.
6. In the Description field, type any name you would like to use to identify the account.
This is the name that will appear in your list of accounts.
7. Using the rest of the information you gathered, complete the rest of the fields.
Be sure to click the checkbox to enable the "Use authentication when sending mail" option.
8. If desired, click the Account Options tabs to change the default account behavior.
9. Click OK when you are finished.

This information applies to: Eudora
In Eudora, go to the Tools menu and select OPTIONS.
Make sure the box "Allow authentication" is checked. (It is under the SMTP server field)
Click OK

Troubleshoot 550, 553, and relay-prohibited errors

This information is copied from Microsoft- Click here to read the entire article

Relaying occurs when an e-mail message is sent to an e-mail address whose domain (the name after the @ symbol, such as is not processed by the Simple Mail Transfer Protocol (SMTP) (Simple Mail Transfer Protocol (SMTP): A common protocol that is used to send e-mail messages across the Internet.)or outgoing server that the sender is requesting to deliver the message. The SMTP server must connect to another SMTP server to relay the message.
When you send an e-mail message that encounters a relay error, your SMTP (outgoing) e-mail server might return your e-mail message with an error message such as one of the following:
  * The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was ''. Subject: '', Account: '', Server: '', Protocol: SMTP, Server Response: '550 ... Relaying Denied', Port: 25, Secure (SSL): No, Server Error: 550, Error Number: 0x800CCC79.

* "The message could not be sent because one of the recipients was rejected by the server. The rejected e-mail address was ''. Subject '', Account: '', Server: '', Protocol: SMTP, Server Response: '553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)', Port: 25, Secure(SSL): No, Server Error: 553, Error Number: 0x800CCC79.

The exact error message might vary, depending on your Internet service provider (ISP) (ISP: A business that provides access to the Internet for such things as electronic mail, chat rooms, or use of the World Wide Web. Some ISPs are multinational, offering access in many locations, while others are limited to a specific region.). Some ISPs might not return an error message when they detect outgoing messages as unsolicited commercial e-mail. In such cases, your message might appear to be sent normally? it leaves the Outlook Outbox and appears in Sent Items? but it is never actually delivered to the recipient.

Your message was rejected because the SMTP (outgoing) e-mail server did not recognize you as an authorized user.
SMTP is the protocol? standards that computers use to communicate with each other? that most e-mail servers use to send e-mail messages across the Internet. When you use an e-mail program, such as Outlook, that lets you store your e-mail messages on your computer, you need access to an SMTP server to send e-mail messages.
Note Web e-mail systems similar to MSN® Hotmail® and Yahoo! Mail are used differently, and this article does not apply to those e-mail accounts.

Your ISP to the rescue
As junk e-mail volumes increased, network administrators? the people responsible for managing your ISP servers? began placing restrictions on their SMTP e-mail servers. These restrictions help prevent just anyone from using, or abusing, an e-mail server. Think of it like this? a telephone in the lobby of your organization was available for anyone to use whether they worked at your organization or not. Now only the employees are permitted to use that phone.
There are several types of restrictions in use today:

NOTE: WE REQUIRE THIS: * Require SMTP authentication Just as you must use a password to access your POP3 (incoming) server for your e-mail messages, this option requires that you provide a user name and password to send e-mail messages through the SMTP server. Usually, these are the same user name and password used for the POP3 server; however, they can be unique.

NOTE: AND/OR REQUIRE THIS: * Require that you connect to the ISP POP3 (incoming) e-mail server first When you connect to retrieve your new e-mail messages, you typically connect to a POP3 (incoming) e-mail server. You are required to provide a user name and password to access your mailbox. A network administrator can configure the server so that if you first connect and authenticate with the POP3 e-mail server, it will approve any request that you make to send an e-mail message through the normally restricted SMTP outbound server.

Either one of the above fixes will work but it is best to just choose "allow authentication" or "my server requires authentication" when setting up your e mail account. That will prevent any future headaches with SMTP