You need a tool to send bulk cold emails. The best way is to write a sequence of emails which you can send individually or as follow ups to previous emails sent. The tools often also include tracking metrics and ways to determine if your messaging is working or needs to be improved by adjusting your subject line or the offer in your email.
Some of the more popular tools include:
You can chose between a tool that just sends cold emails, or others that send cold messages from email, and LinkedIn. This is called multi-channel outbound messaging. It's more and more critical to include other ways of reaching a prospect than just relying on cold email.
The most common channels after email are LinkedIn, followed by Twitter. It's okay to start with just email and learn how to incorporate LinkedIn messaging at a later date.
Once you have your sequence of emails written, you can then find a list of prospects to send to. Some common tools for finding leads are:
Most of these services have some data that is out of date so it's very important you also do research on these leads to make sure their email, current job and current job title are correct. The more time you spend here, the higher your campaigns will perform.
There are also service you can use that will do this for you such as https://coldemail.studio.