Some outreach mistakes cost you a campaign. A few cost you assets you cannot easily replace — your domain, your reputation, occasionally a legal position. These are ordered by what they actually cost, not by how often they are mentioned.
The most expensive mistake available, and the easiest to avoid. When deliverability degrades — and eventually something goes wrong — it takes your invoices, your client threads and your password resets with it. You discover this weeks later when a client says they never received something.
A separate domain costs about twelve dollars a year. Setting one up properly takes an afternoon.
Purchased lists are stale, unverified, and frequently contain spam traps — dormant addresses maintained specifically to catch senders who did not verify. Hitting one damages your reputation immediately, and no amount of good behaviour afterwards undoes it quickly. In the EU and UK, using bought personal data also puts you on the wrong side of data protection law.
No SPF, DKIM or DMARC means a large share of your mail is filtered before anyone reads it. People send for months without realising, conclude that cold email does not work, and abandon a channel that was never actually running. Twenty minutes of setup.
Two hundred messages in an hour is a machine signature that no content disguises. Worse, it is usually the panic pattern — outreach neglected for weeks, then done all at once when a quiet month arrives. That is the version most likely to burn the domain.
Someone asks not to be contacted and receives another message four months later because a different campaign pulled the same list. This generates complaints, which are the fastest reputational damage available, and in most jurisdictions it is unlawful. Opt-outs must be permanent and global across every campaign — not a per-campaign setting.
A merged company name inside an otherwise identical template. It is recognised instantly and lands worse than no personalisation, because it demonstrates you wanted to appear attentive without being it. What genuine personalisation requires.
When results are poor, the instinct is to send more. If a hundred well-targeted emails produce nothing, a thousand produce nothing at greater risk. Volume multiplies whatever your targeting already is — which is an argument for fixing the profile first.
A no honoured cleanly leaves a door open; a no ignored closes it permanently and often produces a complaint. The same applies to the fifth follow-up on silence. Two follow-ups, then stop.
Sending from the domain your business depends on. Every other mistake on this list costs you a campaign or a period of poor results. That one can take down the email your invoices, contracts and client relationships travel through, and you often do not notice until real damage has been done.
Sometimes, with weeks of stopped sending, a fixed root cause and a slow rebuild. Often it is faster and cheaper to start with a fresh domain — twelve dollars against weeks of uncertain recovery. Which is the argument for never risking a domain that matters in the first place.
Keep a single exclusion list at the level of your whole operation, not inside individual campaigns, and check every send against it. Any tool that treats unsubscribes as a per-campaign setting will eventually email someone who asked you to stop — and that is a complaint waiting to happen.
Yes, if done at moderate volume with the infrastructure right. The risks concentrate almost entirely in shortcuts: bought lists, skipped authentication, burst sending, a shared domain. A separate domain, verified records, twenty messages a day and a real profile is a durable channel rather than a gamble.
The Cold Outreach Machine finds the companies you sell to, writes a different email for each one, and sends them on its own — paced, inside working hours. US$299.99, paid once, live setup call included.