Not sure about how opera mail works but if its anything like the account setups in OE or pimmy then your pop3 and smtp server should show 127.0.0.1 and your account or user name should have the # in it
for example if your user/account name is ash and you were with mail.ru ,it would be

ash#pop.mail.ru
Check your account settings that mail is being retrieved on 110 and sent on 25,then check that both pop and smtp have 127.0.0.1 as default , then check your account user name has the hash#inserted.
me