For this question, let's assume I needed to send an important email to a potential customer. Because of a problem with my email client, which rarely happens, two copies of the email are in my Sent folder (both there and on my webmail client). It looks like the message has sent twice, although I'm not 100% sure about that because I can't see the recipient's inbox.
I am wondering if I need to send another email to apologize for this or if that would just be adding more noise to this person's inbox. Is there a business/workplace etiquette convention for this?