A single welcome email works well when your signups arrive with roughly the same intent from the same source. The moment you have meaningfully different cohorts, one email cannot serve them all without being mediocre for everyone.
Common splits worth acting on: organic signups versus invite signups (they are starting from different places socially), high intent source signups like people who came from a comparison page, and users who entered through a specific integration or use case landing page. Each of these groups knows something different about your product. Your welcome email should meet them where they are.
In GetFluxly, you can branch an automation at the entry point based on a trait set at signup, like the referral source, the plan, or whether the signup was self serve or invited. Each branch sends its own welcome email, tailored to that context, but all of them share the same structural principle: one job, one CTA, fired immediately off the signup event.
For a full picture of how the welcome email connects to the emails that follow it, see the guide on user activation emails and the broader SaaS onboarding email sequence.