Can I use iCloud Mail for business?

Outgoing servers are always SMTP. IMAP is one of the incoming server methods.

Set your iCloud email account up manually. For the incoming server use these settings:

• Server name: imap.mail.me.com
• SSL Required: Yes
  If you receive errors when using SSL, try using TLS instead.
• Port: 993
• Username: The name part of your iCloud email address (for example, emilyparker, not emilyparker@icloud.com)
• Password: Your iCloud password

For the outgoing server use the settings for your domain's email service.

It looks as if what you should do is first to set up your domain email in Mail. Then set up the iCloud mail account in the usual way, and having done this go to Mail Preferences>Accounts (not Mail>Accounts) and select the iCloud account. Set the SMTP server using the drop-down menu to your domain and check 'Use only this server'.

(This is Mail on Mavericks, I don't know if Yosemite is the same.)

You don't even need to set up your domain email in Mail.app. Just add it as an additional Outgoing Mail Server (SMTP) for the iCloud account you set up. You'll see the option to "Edit SMTP Server List" at the bottom of the drop down menu that you mentioned. Set it up per your domain provider's instructions.

Personally I recommend associating a separate iCloud address to each domain email. You can sign up for multiple iCloud accounts. If you would like an iCloud only account, I'd dedicate one to just that and not muck that up with any personal/business domain stuff.

Abraham, there's no need to create Alias accounts to accomplish anything we've been discussing. As a matter of fact, doing so will prevent you from using those aliases as fully functional, standalone accounts in the future.

Yes.

You will need the SMTP server address for your domain email, which if you don't have to hand your service provider will tell you.

Perfect. Thanks Roger and Ergload. This made it super simple. I added the extra SMTP server, kept icloud and my current domain. Great solution. Thanks so much. Apple should make this a regular "product"!

Roger

One odd thing, since I added the Google account to Mail there are some icloud messages that go to my junk folder that aren't marked Junk. I tried everything including reseting junk settings, changing the setting to leave junk mail in the inbox, and so far nothing is working. I guess I could delete the google account from my Mail app since now all outgoing mail uses that SMTP server anyway. But it's nice to have it there in case I want to check the folders. Have you seen this before?

This action is probably taking place on the server - quite apart from the junk filter in your Mail application, there is a junk filter built into the iCloud mail server. I quote from their Help:

Click the Junk folder in the sidebar.

Select a message, then click the Not Junk button in the top right of the message window.

The message is moved to your Inbox. Subsequent email messages from the same sender are no longer automatically marked as junk.

It's in regard to amg1957's question

Roger this has all worked very well. One new issue: somehow in my Mac Mail client the SMTP server was set back to icloud instead of my domain. Is there something that does that I am doing? Any way to put a check on it?