Everyone knows the thread with forty replies where the decision is hidden in message twenty-three. Summarising it is the most common request people make of an AI assistant on mail, and one of the easiest to get wrong. A few habits help you summarise long email threads with AI and get summaries you can rely on.
- Name the thread, the person or the project, and say what the summary is for.
- Ask for decisions, open questions and owners, not a retelling.
- Check the source message for anything that matters, especially dates and amounts.
When a summary helps
Where it helps
- Long threads you joined late.
- Handovers when a colleague is away.
- Preparing for a meeting with a customer.
- Finding who promised what.
Where to be careful
- Contracts and legal wording.
- Amounts, dates and deadlines.
- Tone and sensitive messages.
- Anything attachments decide.
Prompts that work
What each role needs
| Role | Useful summary |
|---|---|
| Sales | Customer wishes, promises made, next step and date. |
| Support | The problem, what was tried and what the customer expects. |
| Project manager | Decisions, open questions, owners and deadlines. |
| Executive | Where it stands, what is blocked and what needs a decision. |
The same thread produces four different summaries. Say who the summary is for, and the result gets shorter and more useful.
What to check in the result
- Names and datesCompare them with the source message.
- NumbersPrices, quantities and deadlines must match exactly.
- Missing piecesAsk what the thread does not answer.
- SourceAsk for the message the summary is based on, and open it.
Example: before and after
Before
- Forty replies over three weeks.
- Decision hidden in message twenty-three.
- Ten minutes of scrolling before the call.
After
- Decisions, open questions and owners in five lines.
- The source message named, so you can check it.
- Two minutes, and you walk into the call prepared.
Example, not a real customer. The saving depends on the thread, so measure it in your own pilot.
Common mistakes
- Asking for a summary with no purpose, which gives a retelling.
- Trusting numbers and dates without opening the source.
- Summarising a thread that sits in a closed folder and expecting a result.
- Forgetting that the summary is a draft of your understanding, not a record.
Keep it safe
Summaries are only as safe as the access behind them. With AddSync AI the assistant reads a limited number of messages per question, only those that pass company data filters, and does not store what it reads. If a thread sits in a closed folder, the assistant will find nothing, and the journal shows the attempt. See data filters.
Make it a team habit
Agree on three or four standard prompts and keep them in a shared note. Teams that do this get consistent summaries and spend less time rephrasing. The prompts in 7 AI prompts for meetings are a good starting list.
Questions and answers
Can AI summarise a thread with attachments?
It depends on the data filter, which can allow or block attachments. Check the setting for your company.
How long can the thread be?
Each question reads a limited number of messages, set by IT. Ask for a summary by period if the thread is very long.
Is the summary legally binding?
No. It is a working aid. Check the source for anything that matters.
Will the AI send the summary?
No. It can save a draft that you read and send yourself.
Try it on your longest thread
Connect a few mailboxes for 14 days and see how much time summaries save.
Keep reading
- What is Mail AI?: The idea in five minutes.
- AI for sales teams: Customer threads and follow-ups.
- Claude for email: Setup and rules.
- 14-day AI pilot: A plan that ends with a decision.
Written by the AddSync team.
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