Product update email template, from https://devrelay.so/blog/product-update-email-template
Replace everything in [brackets]. The second block is a filled-in example for Acme, a made-up help desk.

# 5. Breaking change or deprecation email template

Subject: Action needed by [date]: [what changes]
Preview: [Who is affected] need to [the one step]

Hi [first name],

On [date], [what stops working or changes]. You're getting this
because [why they're affected: they use the feature, the integration,
the old endpoint].

What to do: [the one step, as specifically as possible].
It takes about [time].

[Button: link to the guide or the setting]

What happens if you don't: [the consequence, plainly].

Why we're changing it: [one sentence].

If you're not sure whether this affects you, reply and we'll check
your account.

[Your name], [role] at [Product]

---

Example:

Subject: Action needed by October 30: reconnect Slack
Preview: Acme notifications in Slack stop until you reconnect

Hi Priya,

On October 30, the old Slack connection stops working. You're getting
this because your workspace sends new conversations to #support in
Slack.

What to do: open Settings → Integrations → Slack and click Reconnect.
It takes about a minute and keeps your channel and rules.

[Reconnect Slack]

What happens if you don't: Acme stops posting to Slack on October 30.
Nothing else changes, and you can reconnect any time after.

Why we're changing it: Slack is retiring the kind of connection we
used, and the new one asks for fewer permissions.

If you're not sure whether this affects you, reply and we'll check
your account.

Sam, product at Acme