The tone and style of your apology email should match your brand voice and your audience's expectations. To make your message more clear and convincing, consider using a subject line that reflects your apology and grabs attention (e.g. “We’re sorry for the delay” or “An update on your order”). Begin with a personal salutation, using the customer's name if possible, to show respect and sincerity. Be honest and direct when explaining what happened, without making excuses or hiding behind jargon. Show empathy and compassion by acknowledging the customer's frustration, disappointment, or inconvenience, and thank them for their patience or feedback. Additionally, provide a solution or compensation such as a refund, discount, freebie, or promise to fix the issue; make sure it is relevant, reasonable, and timely, and that you follow through on it. Finally, end with a positive note such as a reassurance of your commitment to quality, a request for feedback, or an invitation to contact you for further assistance. Sign off with your name and contact details.