MacOS doesn't recog. "mailto" addresses

Please try setting Mail as your default email reader. Below link will provide help to you to perform the Change your default email app.

https://support.apple.com/en-us/HT201607

bobhwc Said:

"MacOS doesn't recog. "mailto" addresses: iMac OS Mojave: On websites under "Contact," any Web browser I use gives me the message, "MacOS doesn't recognize Internet addresses starting with "mailto:"

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A Few Thoughts:

• Boot into Safe Mode:

Hold Down: [shift key] upon boot. In Safe Mode, items run by default with all preferences set aside.

• Try a New Browser:

Try a new browser (i.e Mozilla Firefox or Google Chrome). If that works, then it is an issue with your browser.

• Reinstall macOS Mojave:

Safari is built into the macOS, so you'd have to reinstall the macOS to fix it, in that case.

• Elsewise - it is the author of the site at fault, and nothing on your end.

So...

Report this as a Bug to Apple:

1. Go Here: Feedback - Safari - Apple
2. Select: "Bug Report" for the "Feedback Type"
3. Proceed from there as necessary

Meaning adding Gmail email account in Mail.

How to add / remove email account: https://support.apple.com/en-in/guide/mail/mail35803/12.0/mac/10.14

Gmail is an email account from google and not a email client / program.

I'm Sorry, i've not used other email client. I have set up my gmail account in the Apple mail client and it works fine.

Someone else from the community who is using other email client should be able to help you or answer.