Outbound work starts with a profile of the ideal candidate, then a search across professional networks, CV databases, communities and past applicants. Recruiters use Boolean strings and filters to build a list, then send personalised messages, usually in short sequences of two or three touches. Response rates, replies that turn into conversations and how many sourced people reach interview are the usual measures of how well it is working.
Outbound sourcing is most useful for scarce skills and senior roles, where the best people are rarely applying. It is slower and more expensive per candidate than advertising, so it works best when targeted. Sourced candidates should still be assessed against the same criteria as applicants, and outreach should respect data protection rules on how contact details are found, stored and used.