I received an e-mail with a return address. How can I find a street
address or phone number that corresponds to this e-mailer?
Specifically, the address is relaistech.com. The name of the
corporation would be helpful, also.

Dear sweetpea51,

The registrants of .com-domains can be found in the NIC.com Whois
Database:
http://www.nic.com/nic_info/whois.htm

In this specific case, the company owning the domain name
"relaistech.com" is:

Relais Technologies, Inc.
1010 Powers Place
Alpharetta, GA 30004
USA
Phone: (770)569-0403

I found the address and the phone number confirmed by a cross-check
using the online phone directory Switchboard.com:
http://www.switchboard.com/

According to the Corporations Database of the Georgia Secretary of
State, the company Relais Technologies Inc. was filed on 26 February
2001, the registration number is 0109960.
http://www.sos.state.ga.us/corporations/corpsearch.htm

Hope this answers your question!
Best regards,
Scriptor