As the webmaster of the Ohio Transit Hiker's Resource with my own paid domain name, my e-mail address is @othr.info. Unfortunately, that also makes me the post master, who handles all the SPAM. Typically, a company with their own domain would have the resources to design filters to keep all the bad stuff out. Right now, I have neither the time or computer equipment to experiment with such things.
In these cases, I learned that if you set such an e-mail address to forward to a Gmail account, their SPAM filters ought to do the trick. Then you set Gmail's outgoing to send as the email address on your domain and with luck, the people on the other end will never know that there was ever a change.
At the moment, I'm typing my old Outlook 2007 filters into Gmail. Downtrail, I don't want to get too bothered by my inbox, so I'm applying filters to sort and organize my email into folders. They both have their export and import features, but I don't trust that they'll match up on Google's side if it's anything like importing my address book was.