I have a field 'Priority (dropdown with option 1,2,3)'. When user add new item to list and select 'priority' as 1 , subject line auto include keyword "important". I have created workflow in SPD 2010 and used 'send an email' action. By default subject line is "Ticket has been created".
When a user selects priority as 1, the subject line should include "Important-Ticket has been created" and if a user selects 2 or 3 then subject line need to be just "Ticket has been created".