These messages are transactional: about an order the customer placed, sent to every buyer, with no promotion. Keep your standard footer with your address and a preferences link. Have counsel review the option notice.

Delay notice, email

SUBJECT    Your Order Is Running Late
PREVIEW    new date inside, and your options

Hi [first name],

Your order [#1234] is running late. It should now arrive
by [Thursday, October 8], instead of [Monday, October 5].

What happened: [the carrier missed its pickup from our
warehouse on Tuesday].

What you can do:
  Wait for it          Nothing to do. We'll write again if
                       the date moves.
  Cancel for a refund  [Cancel order] (one tap, full refund
                       within 7 working days)
  Swap it              [Choose something in stock]

[Only if the recovery grid calls for it:]
We've added a [$X] credit to your account for your next order.

[Name], [Brand] customer care
Reply to this email to reach a person.

[Brand, postal address] | Email preferences

Delay notice, SMS

[Brand]: Your order #1234 is running late. New date: Thu Oct 8.
Wait, cancel for a refund, or swap: [short link]. We're sorry
for the delay. Reply STOP to opt out.

Send by SMS only to customers who opted in to order updates by text.

Can’t ship on time: the option notice

SUBJECT    We Can't Ship Your Order On Time
PREVIEW    please choose: wait or cancel

Hi [first name],

We can't ship [item] from order [#1234] by [the date we
promised]. We now expect to ship it by [revised date].
[Or: We don't know yet when we can ship it.]

You can:
  Wait     [I'll wait]
  Cancel   [Cancel for a full refund]

If you cancel, we'll refund [$X] within [7 working days].

[If the delay is 30 days or less and this is the first delay:]
If we don't hear from you, we'll ship it when it's ready.
[If longer, indefinite, or a second delay:]
If we don't hear from you by [date], we'll cancel this item
and refund you in full.

[Brand, postal address] | Email preferences

Apology with remedy, first failure

SUBJECT    Your Order Arrived Damaged. A Replacement Is On Its Way.
PREVIEW    shipped this morning, arriving by [date]

Hi [first name],

Your [item] arrived damaged. That's on us.

A replacement shipped this morning and should arrive by
[date]. You don't need to send anything back.

We've also added a [$X] credit to your account for your
next order.

[What we've changed, only if it's true: We've moved this
item to a sturdier box.]

[Name], [Brand] customer care

[Brand, postal address] | Email preferences

Primary contact reasons

WHERE IS MY ORDER          no update, customer asking
LATE AGAINST DATE SHOWN    past the checkout date
DAMAGED                    arrived unusable
WRONG OR MISSING ITEM      any line wrong, short or absent
LOST                       never arrived, or marked delivered
CHANGE OR CANCEL ORDER     after checkout, before shipping
DISCOUNT OR CODE           didn't apply, or unclear
PRODUCT QUESTION, BEFORE   pre-purchase question
PRODUCT USE, AFTER         how to use, results, fit
BILLING                    unexpected or unclear charge
SUBSCRIPTION               skip, change, cancel
RETURN OR EXCHANGE         start, status, refund
ACCOUNT                    login, details
OTHER                      review monthly; split anything over 5%

The delivery check

IN THE DELIVERY CONFIRMATION EMAIL
  "Did everything arrive as expected?"
  [Yes]  [No, something's wrong]

"No" opens a short form: damaged / wrong or missing /
not received / other, with an optional photo.
Every "no" gets a same-day reply and a grid remedy.