The SMTP server takes care of handling the mail flow from the sender to the recipient. The SMTP server works on the SMTP protocol i.e. Simple Mail Transfer Protocol. The message sent by the sender is first delivered to the SMTP server after that, the SMTP server delivers it to the receiver. The mail is like below: Mail user agent (MAU)/mail client/ webmail >Mail transfer agent (MTA)/ SMTP server. The mail is then relayed to another incoming server or is immediately delivered to the recipient if the recipient domain is directly connected to the server. If the recipient server is down or busy then the message dropped by the SMTP host is stored in the backup server.
The above mail flow seems simple. But several situations may arise when the SMTP server fails to deliver the message or the user faces troubles while delivering the mail.
Various error messages will be prompted at the screen. The most common among such error messages are: "550 Requested action not taken: mailbox unavailable" or "421 Try again later", other SMTP errors and reply codes
In this article I am going to discuss the Numeric Code: 5.3.5.
This numeric error code indicates the server loop back situation. In such case, the SMTP server loops back to itself because of configuration settings done for loop back.
How to resolve the Numeric Code: 5.3.5?
If you have multiple SMTP virtual servers configured on your Exchange computer:
• If your Exchange server has multiple SMTP virtual servers on it then, check that unique incoming ports are being served by the virtual servers. And also ensure that you have a valid configuration for the outgoing SMTP port. Also check that you haven’t set the ‘All Unassigned’ option for the multiple virtual servers.
• You also need to verify the configuration of the server connectors to prevent back loops. The connectors should not hold back the address space of the local organization. The connectors can have the address space of the local organization if you are sharing the domain and have enabled the ‘Use DNS to route to each address space on this connector’ option.
Follow the given steps to share an SMTP address space in Exchange 2000/2003 Server:
You need to do some configuration settings to the Microsoft Exchange Server 2000/2003 in order to make it support a shared SMTP address space.
To do so, you can use two methods:
• Share the same SMTP address space with a different e-mail system
• Share the SMTP address space by using contacts to redirect e-mail to a remote e-mail system
How to Share the same SMTP address space with a different e-mail system?
What happens when the e-mail system is not authorized for some particular SMTP address space? What happens when the recipient may not be able to receive the message? In such case, a non- delivery report will be generated indicating that the message cannot be delivered to the recipient due to some reason.
Multiple email systems can be configured and chained together to share same address space. Messages from the first e-mail system are transferred to the second e-mail system, then from second to third and so on till the message is delivered to the recipient. If the message couldn’t be delivered to the recipient, then a non-delivery report is generated by the last email system in the linked chain.
You need to authorize Exchange for the primary SMTP address space specified in the default recipient policy.
For that you need to:
• Add the shared SMTP address space to another recipient policy,
• After that make it as the primary SMTP address space,
• Then open SMTP Address Properties dialog box and un- select the checkbox ‘This Exchange Organization is responsible for all mail delivery to this address’.
Note: If Exchange is authoritative for a SMTP address space then it cannot be shared. To check if Exchange is authoritative for a particular SMTP address space or not, follow the given steps:
1. Open Exchange System Manager, Open the recipient policy Properties by right-clicking it.
2. Open E-Mail Addresses (Policy) then select the e-mail address and Click Edit.
3. Now check if Exchange is authoritative for the SMTP address space or not.
4. If the checkbox ‘This Exchange Organization is responsible for all mail delivery to this address’ is not checked then Exchange is non-authoritative for the SMTP address space. Otherwise it is authoritative for the SMTP address space if this check box is selected.
If you want to share the SMTP address space with a different email system follow the given steps:
• Modify the default recipient policy by editing the primary SMTP address space.
• Do Configuration settings for the shared SMTP address space
• Remove message forwarding for unresolved recipients by modifying the SMTP virtual server properties
• Configure SMTP connector for the shared SMTP address space
• Restart the Routing and SMTP services
You can also share the SMTP address space by using contacts to redirect e-mail to a remote e-mail system.
Follow the given steps to Share the SMTP address space by using contacts to redirect e-mail to a remote e-mail system:
• Set the recipient policies Configurations so that can be used with contacts
• Add the contacts to Active Directory to represent remote users
• Remove message forwarding for unresolved recipients by modifying the properties of SMTP virtual server properties
• Route e-mail to the remote e-mail system by creating an SMTP connector
• Restart the Routing and SMTP services
Using the above method described in the article, the Numeric Error Code: 5.3.5 will be resolved. Read my next article to know the step by step detailed procedure for sharing the SMTP address space by using contacts to redirect e-mail to a remote e-mail system.