It you are clicking the link and being shown a web page that states "This website has been classified as malicious" then you will most likely find that the url of the page is something similar to
https://....safelinks.protection.outlook.com/.....
which means that your email service is using part of Microsoft's Advanced Threat Protection, also called Microsoft Defender, usually through Outlook 365. There are known issues with Microsoft's ATP/Defender identification of web pages and they do not provide a means of addressing their incorrect listing of a site except by the receiving account.
To verify any site as being safe there are many free resources on the web that you can use. Some of these resources are shown below:
Google https://transparencyreport.google.com/safe-browsing/search?hl=en
Trend Micro https://global.sitesafety.trendmicro.com/
URL Void https://www.urlvoid.com/
ScanURL https://scanurl.net/
Site Checker https://sitechecker.pro/website-safety/
or any of the many others available.
In most cases, if your email client has not rewritten the link in the email, you can simply copy the link and paste the emailed link in the URL navigation bar of your browser bypassing the Microsoft message. If the URL has been rewritten, it will display the https://....safelinks.protection.outlook.com/..... and you will need to request that the company who sent you the link either send you the alternative link or send it to another email account such as Gmail, AT&T or other provider.
Microsoft's documentation on this and how to address the issues within the Office 365 email system can be found here: Complete Safe Links overview for Microsoft Defender for Office 365 - Office 365 | Microsoft Docs.