Email is the default workflow tool at most small businesses, and most of the time it's adequate. Customers send requests, the team replies, somebody forwards the thread to whoever needs to know. Decisions get made in the back-and-forth. Files get attached. Knowledge accumulates in inboxes. The system works, in the way that an extension cord works as a permanent installation — until you grow enough that the limits show up.
The limits are predictable. New hires can't find context — every decision lives in somebody else's sent folder, and you can't ask the inbox to remind you of the time you discussed this exact thing. People go on vacation and the work stops, because only they know what's in their thread. The customer asks a question they asked six months ago and you can't find the previous answer. Two team members give the customer different answers because neither knew the other had been on the previous thread. Each of these is a small cost. Added up, they're a real drag on the operational layer.
The migration we recommend most often is gentle: move the workflows that have the clearest pattern of "multiple people need to see this" out of email and into a tool that's designed for that — a shared inbox tool like Front or Help Scout, a project tool like Linear or Asana, a CRM if it's customer interaction. Don't try to move everything at once. Move the workflow where the pain is most acute, and stop there for a quarter. If the team adopts it (they will, if you picked the right workflow), keep going.
What this is not is "email is bad." Email is fine for the one-off conversation, for the asynchronous correspondence, for the document trail. What it's not fine for is the operationally-critical workflow that needs to outlive any one person's inbox. The test: would a new hire be able to find this thread? Would the team be okay if the person handling this thread were out for two weeks? If the answer to both is no, the thread shouldn't be in email.