Every brand doing $50K+ per month eventually asks this question, so here is the honest version of the comparison, including the situations where you should not hire us or any agency.
The cost math
A competent in-house email marketer in the US or UK costs $60,000 to $90,000 per year plus benefits, tools, and 2 to 3 months of recruiting and ramp time. A specialist agency runs $36,000 to $60,000 per year at typical retainers (ours is $3,000 to $5,000 per month, public), starts producing in the first two weeks, and can be cancelled month to month.
But the headline salary is not the real gap. The real gap is that good email is three jobs, not one: a strategist who plans the calendar and segments, a copywriter who earns the click, and a designer who makes the brand look premium in an inbox. One hire gives you one of those, sometimes one and a half. You either accept mediocrity on two axes or hire three people.
The speed math
Hiring takes 6 to 12 weeks before day one. Ramp takes another 4 to 8. An agency that lives inside Klaviyo every day skips both: our flow stacks go live within 7 to 14 days of the invoice being paid, because we have built the same eight flows dozens of times.
The risk math
A wrong hire costs 6 months and a severance conversation. A wrong agency costs one month, if the contract is month to month. That is why lock-in contracts are a red flag: an agency confident in its work does not need to trap you. (It is also why we publish dashboard screenshots instead of percentages: proof reduces your risk before you spend anything.)
When in-house actually wins
Honesty section. Hire in-house when: you are past roughly $1M per month and email justifies a dedicated team of three or more; your brand voice is so unusual that no outside writer has nailed it; or email is your core differentiator and you want the capability owned internally forever. In those cases an agency is a bridge, not a destination, and a good one will tell you so.
The hybrid most people miss
Plenty of our clients keep a marketing generalist in-house who owns brand and socials while we run the email and SMS machine. The generalist feeds us launches and content; we turn them into 40%+ of revenue. That splits the work by what each side is best at, and it costs less than either full path.
Want this done for you instead?
We run email and SMS end to end for ecommerce brands doing $50K+ per month, and every claim in this post has a Klaviyo screenshot behind it. Book a free audit, or start with a free popup and welcome email built for your brand.