The delivery slips by a week and it is on our side. The client is one we want to keep. Which version of the email do I send?

Option A is the stronger email because the delay is self-caused and the client is important to retain, so the message should prioritize ownership, transparency, and a firm revised commitment. Option A directly acknowledges that the integration took longer than planned, states both the original and new dates (the 24th instead of the 17th), confirms that everything else is unchanged, uses the firm commitment “we will deliver,” and proactively commits to a short progress note on Friday. This reduces uncertainty, makes the slip explicit, limits perceived damage, and rebuilds trust through concrete follow-through rather than leaving the next step to the client. Option B has real strengths: it is courteous and warm, opens with gratitude, frames the delay as a common integration challenge, and offers to walk through the details. However, for a self-inflicted delay with a valued client, those strengths are outweighed by weaker accountability and transparency. Phrases such as “As often happens with integrations” can sound like normalizing or excusing the delay, “dependencies took more time than we assumed” shifts some agency away from us, “we now expect to deliver” hedges the commitment where firmness matters most, and omitting the original date obscures the size of the slip. The offer to walk through details is also reactive, whereas Option A’s Friday progress note is proactive. While tone and relationship-building are genuinely debatable and Option B is a competent, courteous alternative, Option A is superior on the core criteria for retaining a client after a self-caused slip: clear ownership, full transparency, a firm new commitment, and proactive follow-through.