FIOS is, of course, a Verizon service. 'outgoing.verizon.net' is the correct SMTP server address. However, they've shut down port 25 for all addresses other than something with "@verizon.net" (as an antispam measure, as alanhardisty suggested). So if you're using a different domain name in your email address, you need to switch to port 587. More information, if you want it, is available at
http://www22.verizon.com/ResidentialHelp/FiOSInternet/Email/Setup+And+Use/QuestionsOne/124274.htm