Originally Posted by
jinglish
Yes! Expedia will probably give you the option of applying your Mileage Plan number when booking, and you can contact Alaska to have it added if not. AS doesn't place any restrictions on mileage earning when ticketed by other carriers like, say, UA does.
Though a ticket purchased through Expedia would almost certainly be ticketed by Alaska anyway if it contains only Alaska flights, just like an Expedia ticket containing only United flights would almost certainly be ticketed by United and thus earn United miles. The difference relates to interline tickets ticketed by another carrier, not whether you purchase the ticket directly from the airline or through a travel agent.