Cold e-mailing can work very well if you do it right.

If you're in sales—or run your own business—it is highly likely that you've sent cold e-mails to your prospects. There are some key mistakes everyone makes early in their cold outreaches that you will do well to avoid. Better to learn from other peoples' mistakes than make your own.
Here are some mistakes you might be making, and tips on how to fix them.
Never, ever, ever buy a customer database.
The chances of you buying a customer database that perfectly matches your user persona is negligible. You have a better chance of finding life on our nearest galaxy—you know someone will, but it likely won't be you. Take it from the experts—good e-mail lists are just not for sale, say the good people at Hubspot.
If it's for sale, it means the email addresses on it have already been deemed non-responsive or unqualified for marketing outreach.
Reaching out to an unresponsive list might impact your deliverability. Reputed mailing systems like Mailchimp, CampaignMonitor etc. will blacklist your domain, making it tougher for you to reach out to customers that do matter.
Always personally qualify every lead you e-mail. Let me insert a shameless plug here when I say that personally qualifying every lead is extremely easy with Airboxr—you can get people matching your parameters right within your spreadsheet.
Never send the same intro e-mail to every lead.
Write a different introduction email to every lead. Do a bit of research on the prospect before you reach out. Even if you use a bulk e-mailing software, such as Mailchimp or Sendgrid, you can still customize one sentence (or a paragraph) to make yourself more relevant to each receiver. Keep these points in mind:
- Mention how the receiver might benefit, without actually selling your product.
- Your goal is to get a call/meeting, not to share everything about your business.
- Be specific on why you're reaching out.
- Give the receiver an out, e.g., "If you aren't the right person, do connect me to a colleague who might benefit from speaking to me. Or simply write back and let me know to stop following up.". Receiving a 'no' over e-mail is better than being marked as spam.

Don't forget to follow-up
Cold prospects will rarely respond to your first e-mail, even if it is incredibly relevant. They might star it for later or they might archive it and forget about it. That isn't necessarily a no. Give prospects 2-3 business days to think about your e-mail before you send a follow-up.
Data shows that flooding your prospects’ inboxes with messages is not the answer. The 5th, 6th or 7th follow-up email brings you merely a fraction of the total percentage, so the people who go for quantity don’t seem to have a better reply rate. Source.
That said, don't assume more follow-ups is bad for your business. Every customer is different and you need to determine the best cadence for your user base.
Don't send e-mails without checking deliverability
Oftentimes you may get access to e-mails through external services such as Hunter.io, LeadIQ etc.—but they may simply be outdated. I always suggest cross-checking the e-mails against a deliverability service to ensure the emails are still deliverable. Many e-mail enrichment providers will do it for you. You could also use tools like DeBounce to do this for you. I've used DeBounce API's to create a short formula that works inside of Google Sheets—if you'd like a copy of the script to make this happen inside your GSheets, just write to us at try@airboxr.com and I will send it along.
Accept a No graciously. Ask for permission to keep in touch.
Anecdotally, most sales people go through multiple No's before getting to a Yes. But if you never keep in touch with the prospect, that No is going to remain a No forever. Ask for their permission to allow you to send them an update e-mail every month or quarter. This helps keep them in the loop and enables them to reach out to you when they feel the time is right. It's important that you don't try to sell them again. Don't send them sales-y material, instead send them material from your blog posts or feature announcements. If you know what caused them to say No the first time, come back to them when you've resolved their concern.
You have to get used to hearing crickets whenever you do a cold outreach. And that is alright. You only need a couple of conversions to justify the cold outreach. As long as you keep the above risks in mind, you will do just fine.