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  1. Agustin's Linux Manual
  2. Networks & Servers
  3. About the Author
  4. Table of Contents
  5. IP Addresses Networks and Subnets
  6. Network Classes
  7. IP Address in Decimal Notation
  8. Sub-netting
  9. Designing Subnets
  10. Allocating Subnets
  11. Defining Host Addresses
  12. Variable Length Subnet Mask
  13. Routing Protocols
  14. Classless Internet Domain Routing
  15. Servers - Chapter 9
  16. Apache Web Server
  17. Configuring Apache
  18. Uploading Web Pages
  19. Apache Overview
  20. MIMEMagic
  21. DNS Servers
  22. Welcome to Webmin
  23. Creating the Master Domain
  24. Adding the Reverse Zone
  25. Querying the DNS server
  26. Adding Virtual Domain to DNS Server
  27. Reverse Zone for Virtual Zone
  28. Binding IP Address for Virtual Domain
  29. Virtual Web Hosting
  30. DNS Security Options
  31. FTP Server
  32. Securing the FTP Server
  33. Email Server
  34. Postfix Configuration
  35. Dealing with Identical Users
  36. Configuring Email Clients
  37. Configuring Outlook
  38. Samba Server
  39. Configuring SAMBA Server
  40. The smb.conf File
  41. smb.conf Analysis
  42. Adding Users to Samba

Dealing with Identical Users in the system

Well you got the virtual domain working, but in a practical environment there are times when you have identical users. For example, you have two users named John Doe, one logs in as john and the other logs in as doe.

[root@server2 postfix]# vi virtual_maps DOMAIN velasco john

Analyze this carefully! When you first created the users (John & Doe), by default they belong to the physical host But I will assume that john will receive email from the virtual domain “” and Doe will receive emails from; therefore I will only include john in the virtual_maps file.
The real name may be the same: John Doe, but it has nothing to do with the account name. Note that they are a different physical identity

Forwarding Email

The interesting thing is that you can forward email to another account.

For example:

John can forward his emails to Doe; here is how to do it:

[root@server2 postfix]# vi virtual_maps

From                            |                   To

Note. Each time you update the virtual_maps, remember to update the database; use postmap virtual_maps < virtual_maps and restart postfix.

Which Clients can relay mail

By default, postfix relays mail for authorized networks and authorized domains. If you are in a local area network, you need to enable the mynetworks directive.


#mynetworks =,
#mynetworks = $config_directory/mynetworks
#mynetworks = hash:/etc/postfix/network_table

Insert your appropriate network in here. Make sure not to include relays to the public. If you are having difficulties getting out from your local area network to the outside world; check these settings. Most likely the problem is here.

Note: Perhaps you will see localhost in this trust and relay control section, if you can't sent emails comment the line and try again.

Here is a good command to find out about your network:

[root@server2 postfix]# postconf | grep mynetworks

Which Domains can relay mail

By default all domains listed in mydestination are trusted domains.

       Well folks that's it…