How to setup Google Apps mail services is the best solution for mail company, You have to create an a account at google.com

To activate Google Apps services you must verify that you own your domain. Demo: http://mail.trongdai.com. Verify domain ownership Get Started Guide

Sign in to your hosting account, and go to the DNS management page.
CNAME records may be in sections such as DNS Management or Name Server Management. You may have to enable advanced settings to create a CNAME record. Please contact your domain host directly if you can’t locate the CNAME management options.
(If applicable) Delete the existing CNAME entry for the alias or unique string.
For example, if you’re creating a CNAME record for ‘mail,’ be sure to delete any existing CNAME records for ‘mail.’
Use the information in this table when you create your CNAME record. Terms used to create CNAME records vary by host. Always use google.com for verification and ghs.google.com for custom urls.

Host Name/Alias Value/Destination
Custom URL: www ghs.google.com
Verification: googlefffggghhh12345 (your unique string) google.com

How to verify your owner domain:

Sign in to your domain hosting service and locate the DNS management page. The location varies by service, but can typically be found under Domain Management or Advanced Settings .
Use the following unique string to create a new CNAME record for the daivycorp.com domain:

googleffffffffxxxxxxx

Point the CNAME record to:

google.com

Once you have made the changes, you can verify that the record exists by doing a CNAME lookup for http://googlefffffffxxxxxxx.trongdai.com . You can find several web sites to do automated CNAME lookups by searching for CNAME lookup at http://www.google.com .

When you finish this step google have a alert:

We are checking domain ownership. This may take 48 hours to complete.

Next step active your email Apps by using thirdparty DNS:

Fully Qualified Domain Name (enter your domain)
Record Type MX
Record Value: ASPMX.L.GOOGLE.COM.
If MX Record, MX Value: 1

Repeat steps seven through nine for the following MX record entries:

Record Value: If MX Record, MX Value:

ALT1.ASPMX.L.GOOGLE.COM. 5
ALT2.ASPMX.L.GOOGLE.COM. 5
ASPMX2.GOOGLEMAIL.COM. 10
ASPMX3.GOOGLEMAIL.COM. 10
ASPMX4.GOOGLEMAIL.COM. 10
ASPMX5.GOOGLEMAIL.COM. 10

If you dont understand it, please see Photo can hepl you complete easily