AI that follows up for you: tools that chase replies across email, WhatsApp and Slack

AI that follows up for you exists, but most of it only works in one place. Email tools remind you when someone has not replied, and a few now write the follow-up. Sales tools send a pre-written series of messages. On WhatsApp, LinkedIn and Slack, the options are mostly drafting helpers and customer chatbots. Very few follow a person, rather than a thread, across every app. This guide covers each kind, what it is good for, and where it stops.

What does "AI that follows up for you" actually mean?

It can mean four quite different things, and it helps to separate them before comparing tools.

• Reminders. The tool notices a thread has gone quiet and puts it back in front of you. You still write and send the follow-up.
• Sequences. You write a series of messages in advance. The tool sends them on a schedule and stops when the person replies.
• Drafting copilots. The tool reads the conversation and writes a reply or a follow-up for you to check and send.
• An assistant that owns the follow-up. You hand it a person, and it keeps track of what is open with them in every app, notices when things go quiet, and has the next message ready.

The first three each cover one step. The last one covers the whole job, which is why it is rarer.

What do email follow-up tools already do?

Email is where follow-up tools are most mature. Three are worth knowing.

Gmail nudges

Gmail has this built in. Google's help page says that at the top of your inbox "you can find sent emails that you may need to follow up on," along with emails you forgot to reply to. You turn each kind on or off in Settings. Gmail decides which emails to surface, and it only reminds you: it does not write or send anything. Suits: anyone on Gmail who wants a light safety net for free.

Boomerang

Boomerang is a long-running add-on for Gmail. Its follow-up feature lets you set a reminder when you send an email, and in its words, "You can select to only be reminded if nobody replies, or regardless." It also schedules emails to send later. It has a free Basic plan, with paid plans at $4.98, $14.98 and $49.98 a month billed annually (pricing). Suits: people who want a reliable "bring this back if they don't answer" on email.

Superhuman

Superhuman is an email app that goes a step further. Its Remind Me feature defaults to "if no reply": if nobody answers, the email returns to the top of your inbox, and if someone does, the reminder is cancelled. Auto Reminders set these for you on emails that have not had a reply.

On its Business and Enterprise plans, Auto Drafts then writes the follow-up in your voice when a reminder comes back. Superhuman says the drafts are never sent automatically. Suits: heavy email users who want the follow-up written, not just flagged.

What about sales sequences?

Sequencing tools are the other big group, and they are the ones that actually send follow-ups for you. lemlist is a good example because it goes beyond email. A sequence can mix email, LinkedIn and call steps, and lemlist's help centre describes conditions that change the path, such as sending a LinkedIn message if a lead does not reply to an email.

It can also add WhatsApp steps on its Multichannel Expert and Enterprise plans, as a $20 per seat, per month add-on. Replies from every channel land in one inbox.

Sequences are excellent at what they are for: reaching many people who have not heard from you yet, with the same well-tested messages. They are a poor fit for the people you already work with. A sequence is written before the conversation happens, so it cannot react to what a client said yesterday, or to the fact that they answered you on WhatsApp instead of email. Suits: sales teams running outbound.

Can AI follow up on WhatsApp, LinkedIn and Slack?

Yes, but the tools look different outside email. Most fall into one of three groups.

Drafting extensions. Reple is a browser extension that, per its Chrome Web Store listing, "reads the conversation you're in and drafts a ready-to-send reply in seconds" on WhatsApp Web, LinkedIn and Slack. You choose a tone, then copy or insert the draft. It helps you write faster, but it only works on the chat you have open, so you still have to remember who needs chasing.

Customer chatbots on a business number. Tools such as Jestor and AiTrillion run AI agents on WhatsApp for a business. Jestor describes timed follow-up flows for sales leads that cancel "if customer responds." AiTrillion, aimed at Shopify stores, says its chatbot "can now automatically respond to customer WhatsApp messages," and that "your team can take over a conversation when needed." These are built for a company answering its customers, usually through the WhatsApp Business Platform, not for an owner's own chats. Our guide to using an AI assistant with WhatsApp covers that distinction in more detail.

Plain reminders. Slack lets you hover over any message and choose "Remind me about this", then pick a time. It is simple and it works, but it is a reminder, not a follow-up.

Is it allowed to let AI reply for you on WhatsApp and LinkedIn?

This matters more than most tool pages admit. Both platforms restrict automated messaging on personal accounts.

• WhatsApp says its products "are not intended for bulk or automated messaging," and that this has always been against its Terms of Service. Its messaging guidelines list "bulk messaging, auto-messaging, auto-dialing, or automation to harm WhatsApp or our users" as adversarial behaviour.
• LinkedIn's User Agreement says members may not "use bots or other unauthorized automated methods" to access the service, including to send or redirect messages. Its help centre says members using such tools "risk having their accounts restricted or shut down."

Businesses that want automated WhatsApp messaging are meant to use the WhatsApp Business Platform, with its own opt-in rules. For your own WhatsApp and LinkedIn, a tool that fires off replies by itself is the risky pattern. A tool that prepares the follow-up and waits for you to approve it keeps you in charge of every message sent from your account.

How do they compare?

Prices and plans change often, so check each site before you decide.

What can't these tools do?

Three gaps show up across almost all of them.

They follow threads, not people. A reminder knows that one email went unanswered. It does not know the person replied on WhatsApp an hour later, so it nudges you about something that is already moving, or misses the thread that really did go quiet in Slack.

Someone still has to decide what to chase. Gmail and Superhuman guess from your email alone. Sequences only follow up on people you have loaded into them. Drafting extensions wait for you to open the right chat. None of them reads everything and tells you which three conversations actually need you today.

The follow-up lacks context. A good follow-up says "here is the revised quote you asked for on Tuesday," not "just checking in." That needs the whole history with the person, across every app they use to reach you. We covered why that history ends up scattered in how to keep track of conversations across apps.

What does an assistant that owns the follow-up do differently?

It starts from the person. You say "keep things moving with Sam," and it treats Sam as one contact, whether Sam emails, sends a WhatsApp or messages on LinkedIn. It knows what was promised on each side, notices when the conversation stalls, and has the follow-up written with the context in it. You approve it, edit it, or tell it to keep handling Sam from now on.

That is the gap Mira is built for. You text Mira over iMessage or SMS, or use the web app, and it connects directly to Gmail, Outlook, WhatsApp, Slack, LinkedIn, Google Calendar and your CRM. Because it brings them into one universal inbox, it sees the whole conversation with a person, not just the last email.

Hand it a person and it owns the follow-up: it notices when things go quiet, writes the next message with the context in it, and checks with you before it goes. It reads every conversation, only brings you the ones that need you, and texts you first, much like the assistants in our guide to AI assistants you can text, but with your whole business behind it.

Nothing is sent as you until you say yes, which is also the sensible way to work with WhatsApp and LinkedIn. Your messages are never used to train AI models; the privacy policy has the detail. Mira is free for 30 days, with no card needed.