Because I often take my Pismo (10.2.6) on the road - - and away from DSL at home - - maybe my rank amateur answer will be of asssistance. "On-the-road" almmost always means dial-up and there are several steps that
must be completed before a successful connection can be established. OS X makes it "easy" because so many of the settings are automatically inserted, but only after you make the correct prelimiary steps.
Try this:
1) Look in your Menu Bar for the little handset icon of Internet Connect. Click to dropdown and open Internet Prefs
2) Double check to be sure Date and Time are correct (on-the-road if one doesn't do this and the time zone is changed, a simple but hidden glitch will screw-up the proceedings, royally).
3) Open Internet Pref panel. Be sure all the data under the E-Mail tab are correctly inserted.
4) Open the Network Pref panel and check that Location is corerectly established, also that in the Show cell your connection is properly described. When therein, also click on Network Port Configurations to be sure your modem is propoerly set in default.
5) The PPPoE data should, largely be set by your connection, but check them anyway with your ISP. Same with your ISP's expectations re: Appletalk and Proxy settings.
When you're satisfied, click on the padlock(s) to be sure that they don't revert unexpectedly. Since I assume you're not going to back-pack this Mac anywhere, once set you should be OK. Until I learned how to set the priority of connections in Inrternet Connect, I kep having to fight with the InfraRed connection which is not anything I've ever used.
Finally depending upon your particular e-mail client there are probably application preferences that need to be set and correct in order for everything to work. Otherwise you'll get, as I started doing this procees regularly across 7-10 locations nationwide, mysterious messages that merely tell you something is wrong, without really pointing to where it can be corrected.
Hope this helps rather than merely repeating what you knew already.
