Customer Apology for a Missed Deadline

Write an apology for a deadline I missed. Own the miss, give the new date, and do not make them comfort me. SITUATION What was due: [DELIVERABLE] Original date: [DATE] New date I can actually hit: [DATE] Why, in one clause I am willing to say: [REASON] What I have already done since the miss: [ACTION] What I am offering: [PARTIAL DELIVERY | DISCOUNT — AMOUNT | NOTHING BUT THE DATE] Their name: [NAME] EMAIL First sentence: the thing is late and the new date. Second: the reason, short, no childhood, no "crazy week." Then what they have in hand now, and what will arrive on the new date. If I am offering something, say it once, as a decision, not a negotiation. Ask only if the new date breaks something on their side. Also a version if the new date will slip again: I should send a different email earlier. Write the warning email, to be sent before the date, not after. Do not say "sorry for any inconvenience" as the whole message. Do not blame them unless they missed a dependency I named: [DEPENDENCY OR NONE].