Lemlist

Guillaume Mubesh was running a lead generation agency in Paris, sending cold emails on behalf of clients and getting results. But he knew something was missing: most email automation tools only did basic personalization—replacing a first name here, a company name there. He'd tested heavily personalized outreach with custom images and videos, and the results were dramatically better. Yet no tool existed to automate this advanced personalization at scale. When he asked his co-founders (described as "technical geniuses") how quickly they could build a solution, they said two weeks. He sold his agency shares and they got to work.

In two weeks, they shipped what Guillaume calls a "very ugly beta." The core functionality was there—create email sequences with personalized images—but the user experience was terrible. "You'd need a master's degree in image editing to use it," Guillaume admits. But the beta worked enough to get feedback. He posted screenshots of his campaign results in Facebook communities focused on cold email. The engagement was immediate: 200 people commented interested, 100 signed up (a 50% conversion rate). Guillaume manually built personalized campaigns for each user before onboarding them, turning the broken product into a working service. Users loved the outcomes but hated the tool.

Just three days after his Facebook post, Guillaume received an email from AppSumo expressing interest in launching his product. They offered a partnership in two months. Guillaume realized he had a deadline—and a huge opportunity. He prioritized features by "technical difficulty" and "marketing impact," rushing to build high-impact features quickly. He also planned features to release during the launch itself, creating the perception of constant innovation. Meanwhile, he studied previous successful AppSumo deals, noticing that founder visibility and daily updates drove engagement. He recorded videos introducing himself and the vision.

The AppSumo launch was explosive: in two weeks, they acquired approximately 6,000-7,000 customers and generated "around $170,000 in sales." While AppSumo's lifetime deal model wasn't ideal for recurring revenue, it provided cash flow and, crucially, thousands of users generating feedback daily.

After AppSumo, Product Hunt came naturally. They ranked #1 product of the day and #2 product of the week, closing 50-60 paying customers in recurring revenue—a high conversion rate. The secret was community. Guillaume had built a Facebook group (800-1000 members) and an email list of all users and signups. When they asked for help, people helped enthusiastically. He applied the same principle to LinkedIn: everyone who signed up received a LinkedIn connection request (via an automated script), and he posted 2-3 times per week, reaching 10,000-200,000 views per post. His strategy: nine value-driven posts for every one promotional post, with comment-gated "lead magnets" (like his email-finding guide) creating scarcity and virality.

Guillaume also used cold email himself, targeting head-of-growth at $50M+ funded startups with 30% reply rates by leading with personal value and relationship-building, not sales. Capterra provided social proof: their 250+ five-star reviews made them visible, and he declined paid advertising there because the platform miscategorized them as "email marketing" rather than "sales automation," pitting them against MailChimp instead of their true competitors.

His biggest mistake: launching an affiliate program without guardrails. Within three months, he discovered an affiliate buying Google Ads for his brand name (cheap, high-converting traffic) and pocketing the 30% commission. Worse, some users gamed the system by using VPNs, creating new accounts, and "affiliating" themselves for a 30% discount. He now runs affiliates by invitation and trust only.

Less than two years after launch, Lemlist hit approximately $600,000-700,000 ARR, growing 25-30% month-over-month toward $1M. Guillaume credits grit, kindness, community-first thinking, and obsession with user outcomes. His advice: be patient, provide value first, and use your own product—he discovered gaps in Lemlist's UX by using it for his own outreach. The journey from "very ugly beta" to $650k ARR in 18 months shows that in a crowded market, differentiation through advanced personalization, combined with founder-led community building and product-market testing, can generate explosive early growth.