Dear {Recipient},

Earlier today, we sent you an email {that/about} {subject}. This was sent by mistake due to {error/reason}. Please accept our deepest apologies. We have taken steps to ensure this doesn't happen again.

If you have any questions or concerns, please don't hesitate to contact our customer service team at {email address} and we'll get back to you within {number of} {working days/hours}.

Sincerely,
{Your Name}, {Your Position}

Dear [Recipient],

I am writing to apologize for the unwanted advertising that was sent to you recently. I understand that this was intrusive and I regret that it happened.

At [Company], we take our advertising and marketing efforts very seriously. We are dedicated to delivering only the best customer experience, and we take pride in our commitment to our customers. Unfortunately, we failed to meet that commitment in this instance.

We understand that unwanted advertising can be intrusive and annoying, and we apologize for any inconvenience or frustration that this may have caused. We have taken steps to ensure that this does not happen again.

We are deeply sorry for the inconvenience and regret that this has caused you. We value our relationship with you and would like to make it right. To that end, we would like to offer you a [discount/free product/etc.]. We hope that this will help make up for the frustration that this has caused.

Once again, we apologize for the unwanted advertising and thank you for your understanding. If you have any further questions or concerns, please do not hesitate to contact us.

Sincerely,

[Your Name]

Dear [Name],

I am writing to apologize for the unsolicited messages I have sent you recently. I understand that these messages were unwelcome and intrusive, and I am truly sorry for any inconvenience or discomfort I may have caused.

I want to assure you that I had no intention of bothering or offending you. I was simply trying to reach out and make a connection with someone. I realize now that this was misguided and inappropriate, and I apologize for the disruption it has caused.

I understand that messages like these can be intrusive and annoying, and I want to make it clear that I have no intention of continuing to send them. I will not contact you again without your expressed permission.

I hope that you will accept my apology and understand that I meant no harm. I am sorry for any distress I may have caused and I hope that you can forgive me.

Sincerely,

[Your Name]

Dear [Recipient],

We are writing to apologize for the unwanted communications that have been sent to you from our company. We understand that this has caused you frustration and we want to express our sincerest apologies for any inconvenience this may have caused.

At [Company], we strive to provide our customers with the best possible service. Unfortunately, in this instance, we have failed to meet that standard. We take full responsibility for the unwanted communications that were sent to you and we can assure you that this was not our intention.

We have identified the issue and are taking steps to ensure that this does not happen again in the future. We have implemented additional security measures to ensure that our communications are only sent to those who have requested them.

We understand that this situation has caused you frustration and we want to make it right. As a gesture of goodwill, we would like to offer you a [discount/credit/free product/etc.]. Please contact us at your earliest convenience to redeem this offer.

Once again, we apologize for any inconvenience this may have caused. We value your business and we are committed to providing you with the best possible service.

Sincerely,

[Your Name]

[Your Position]

[Company]