Thank you for the comment, if you are using the OWA for only one domain, you don’t need to buy additional SAN certificate. One SAN Certificate is more than enough

I am trying to setup company exchange 2010 std server fro about 50 users. We have 4 different domains eg com1.com, com2.com, com3.com and company.com. All users have primary email accounts as user@company.com, the other domain names are old domians which the company has kept and I would like users to receive emails from them as well. All the 4 company MX records point to mail.company.com, For OWA etc do I need to purchase SSL certificate for each domain (old domain name are not used to send out emails)

You can accomplish sending two ways. First is to setup outside hosting for the other domain. You won’t point MX traffic there, it will only be used for sending. You create user@domainb.com on that host and setup an IMAP (or POP) in Outlook for those credentials. You’ll have to configure the IMAP and SMTP in Outlook witht he IP address of your shared hosting since the URL of that domain will be pointing to your in house server. When users compose an email they click the Account tab and select user@domainb.com. There is a software solution from Ivasoft.com that will accomplish using multiple SMTP addressing as well but it’s expensive. I’ve used that on Exchange 2003 years ago but not 2007 or 2010 yet.

Please share your solution to fix 2 error:
1. create same username on other domain
2. send email ok, but cannot receive email.

Thanks!
Anh

So i have read everything above and all the comments, i get i can put different Domains into a ainslge server box without any issue.

The issue i a m having is, the 2 companies (same staff) want to be able to receive e-mail from both on one user name, So ABC.com & XYZ.com are recieved into single users mailbox’s. But they also want to be able to SEND from either if they chose using the single user name.

Is this possible, running SBS2011 STD with Exchange 2010

Thanks in advanced for any help regarding this!

Thank you for the comment. I am assuming that you refer Ex1 to first domain controller and Ex2 to additional domain controller.

Yes, you can create DAG with Ex2 server but if the Ex1 is down users will not be able to connect the mail box in the Ex2 and you will not be able to send the mail through Ex2.

In Exchange 2010 all the clients are connecting to the exchange through CAS server only. CAS role is very important in exchange 2010. For sending the mail you need Transport role.

These are the answer of your questions

1. can i put them in one server ? yes you can.
2. can i have a saperate mailDB for every doamin in the smae server ?? Yes you can create separate DB for the different domain users.
3. can i have a saparate CAS for every domain in the same server ??? I am not clear about your question, if your question is about creating UPN suffix for each domain, yes you can configure it, and the steps are below.

Adding a UPN Suffix to a Forest

1. Open Active Directory Domains and Trusts.
2. Right-click Active Directory Domains and Trusts in the Tree window pane, and then click Properties.
3. On the UPN Suffixes tab, type the new UPN suffix that you would like to add to the Forest.
4. Click Add, and then click OK.

is it possible .