Not too long ago, we got a call from a guy who was looking for a job. He had just recently lost his job and wanted to send us his resume. He asked that question you never want to hear in today's day and age:
Where can I fax my resume?
I feel pretty confident in saying that if you need to fax me a resume, you may no longer be qualified for a job. All kidding aside, this is a valuable lesson for job seekers. Not knowing how to utilize modern tools is one thing, but at the very least, don't advertise that fact. Now this gentleman was a very experienced and qualified sales rep. I'd have no qualms about presenting him to a client. It's safe to say he used email and the internet, how couldn't you in a sales job today, but I'm pretty sure the only PC he had access to was his company's laptop, which was taken away when he was let go.
Most people wouldn't be in this situation, but it's a good example of what our netiquette says about us. Don't use things that date you. For instance, we still get a lot of AOL email addresses. That doesn't seem like a big deal, but do you know how to use cloud based storage? Are you familiar with Google Docs? OneDrive? Can you Skype and use social media?
Or did you get a dial up account 20 years ago and it's not broken so why fix it? That tells me you have a certain comfort level. You've had the same email account all these years and never bothered to learn something new. Maybe your kids set it up for you.
Sometimes its the smallest things that can cause a potential employer to throw your resume into the trash can (that would be the recycling bin for those of you who don't still use fax ; )