"Relaying denied" error while sending mail

[Balgovind]

hie,

Whenever I try to send mails, I recieve the following error message - "Relaying denied". I am totally unaware about this error. What does this error message mean ? and how do I remove the same ? can anybody help me providing information about this error message and also the necessary ideas for removing it ?

thanks...

[Techno01]

Relaying Denied error -

A mail server will produce a "Relaying Denied" error when an unauthorized user attempts to send non-local email through the server. Non-local email is email which is addressed to a different server.

Mail servers will not relay mail from just anyone. Otherwise, spammers could flood the mail server, making it do their dirty work. You must be authorized to use a mail server. Unauthorized users will always receive the "Relaying Denied" error.

Note: This error has nothing to do with the software that actually sends the email.

[Techno01]

How to Prevent "Relaying Denied" - To use a mail server, you must prove to the mail server that you are authorized to send email.

Follow the necessary guideline to avoid Relaying Denied error -

• The sender of the email should be a user on the server.
• The "From:" header should be a user on the server.
• If the mail server is on a Local Area Network, it may be necessary to specify the mail server's local IP address, not its name.
• This error can sometimes be circumvented by first checking for incoming email. Some servers are smart enough to recognize that when you are properly authenticated to receive mail, then you should also be able to send mail.
• It is also possible that the mail server will only relay mail for users that are currently connected to the ISP. If you want to be able to send mail when using a different connection, you will need to ask your ISP if "SMTP authenticated login" is supported. If it is, they will give you a user name and password.
• Occasionally, a mail server may require that the email program say hello properly. This corresponds to the HELO or EHLO command in the SMTP protocol. The mail server may require that this command reports a proper domain name that is authorized to send email. Even though this practice is discouraged, some mail servers perform this check as a form of spam prevention.

[deveritt]

There are two solutions for this problem:

1. You configure your MTA to allow authentication via SMTP (SMTP-Auth). Your users then have to change settings in their email clients (e.g. Outlook), i.e., they have to activate Server requires authentication.
   
   
2. You install "POP-before-SMTP" or poprelayd on your server. Your users then have to fetch emails first before they are allowed to send emails for a restricted period of time (mostly 30 min.).

[Techguru01]

Some possible Causes:

• The SMTP server does not allow relaying unless you are sending email from a trusted IP or use proper authentication.
• Microsoft Exchange server: server is setup to block smtp relaying.
• Some servers allow you to send email internally but not to external email addresses.
• Some SMTP servers require the Email User to login and check their POP3 email atleast once on the given IP before they let that user send SMTP mail from that IP. Once the POP3 email is checked using a valid user/pwd, the computers IP is then automatically added to a safe list on the server. This is another way to prevent spamming.
• Relaying denied is a common safety measure used by SMTP servers when a certain email address & its mail server are put on a blacklist for email relay spam
• violations. Many honest mail servers get put on this list because someone broke through and used their server to relay spam. There are various blacklists available and SMTP servers may subscribe to none, a few or many of these lists. Hence you may be able to send email to a blacklisted address through one SMTP server but not through another.

Possible Solutions:

• Make sure with your email administrator that your email server is setup to allow smtp relaying from trusted local internal IP addresses.
• Make sure that your computers IP address is on the list of trusted clients on the email server.
• Some email servers may allow relaying only if you log in and check email atleast once from a given IP address. In this case, you can check your POP3 email first before sending SMTP email from a new computer.
• Some email servers allow smtp relaying only if you log in and check email within the last 1 hour/day etc... In this case, you should use the pop3 authentication method to send email.
• Some servers require you to authenticate before sending email. In this case, use the smtp or java authentication methods.
• Microsoft Exchange: make sure that your exchange server is configured to allow smtp relaying either for trusted IP addreses, or for users that are authenticated.
• Make sure that your email administrator has configured your ip address / account to send internal and external email.