Rules to auto send using a particular account

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Is there a way to set rules so that email sent to a particular domain is
always sent using a specified email account? I see that I can do just about
anything with incoming mail, including forwarding it, etc. But I do not see
that Outlook can be set to use a particular smtp server to send to a
particular domain.

Is that right?

 

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I should have specified, as well...I use Outlook 2007 on a Windows XP
machine. I have three email (pop) accounts set up in Outlook. I find that the
spam filter for my largest client is set to filter out emails that come from
the email servers of my ISP, even when I use my primary email address, which
is tied to my small company's domain. That domain is hosted by Earthlink.

So what I need to do is send emails - and I send a lot of them every day to
the clients staff - via one of my other accounts. But I would much prefer to
automate the account selection process, if that can be done, rather than
having to remember to use that little drop-down menu every time....