MCP

List sourcing methods

TL;DR

  • Four sources in practice: databases, manual research, signals, and your own footprint. Each has a different accuracy and a different cost.
  • Signal-based sourcing — building the list from something that just happened — outperforms static firmographic lists, because it answers why now as well as who.
  • Bought lists are the one method with a specific downside: they are named explicitly among the practices that get senders blocklisted.

Databases

The default. Filter a commercial contact database by your profile criteria and export. Fast, broad, and the accuracy of what comes out is the accuracy of a record someone else collected at an unknown date — which is why verification is not optional (Email finding and verification).

Two habits make database sourcing much better. Filter harder than feels comfortable, because the export is where lists silently become broad. And check a sample of ten records by hand against the companies' own sites before trusting the other ten thousand.

Manual research

Building the list by hand from company sites, industry directories, conference attendee lists, review sites, community memberships or public registries. Slow, accurate, and the only option for segments no database indexes well.

It is also where the best A-tier lists come from (Segmentation and tiering), because the research that builds the list doubles as the research that personalizes the email.

Signals

Sourcing from something observable that just changed — a role being hired for, a funding round, an office opening, a technology added or removed, a leadership change, a product launch. The signal-driven school argues this is the highest-leverage sourcing decision available, on the grounds that targeting and timing dominate copy [1].

The advantage is structural: a signal-sourced list arrives with a reason for the email attached, so the relevance problem is largely solved before anyone writes anything. Timing is the whole subject of Triggers and timing, and the underlying idea — that a window of dissatisfaction opens and closes — is old and well-documented [2].

The constraint is volume. Signals are rare by nature, which makes them a source of quality rather than of quantity, and a reason to run continuous small campaigns rather than occasional large ones.

Your own footprint

Cheapest and most overlooked: people who visited your site, attended your webinar, follow your company, opened a previous campaign, or work at a company you have already sold into. Warmer than anything above and often available at no cost.

Note that some of these have consent implications that cut both ways — a prior relationship can create implied consent under some regimes, and a prior opt-out is absolute regardless of source (Staying legal in a nutshell).

About bought lists

Purchasing a list is fast, cheap, and the single sourcing method with a named reputational cost: the major blocklist operator lists purchased and scraped addresses, and email appending, among the practices that make a sender a listing candidate (2025) [3]. Beyond that, bought lists are stale by construction, usually shared with everyone else who bought them, and full of addresses that will bounce or land in a spam trap.

The pattern to internalize: the cheaper the list was to acquire, the more of your sending reputation it will spend.

References

  1. Eric Nowoslawski — The winning cold outbound formula (interview, ~2024-25)
  2. Craig Elias & Tibor Shanto — SHiFT! Trigger Event Selling (book preview chapter, 2010)
  3. Spamhaus — Spamhaus's take on cold emailing, aka spam (resource hub, June 2025)