You can't get around the 255 character limit of the hyperlink,
but you can change your approach and use the Worksheet_Followhyperlink event to call a macro that will shell out to Thunderbird.

I put some email addresses on rows 10 to 30 and copied your existing other stuff.
Ran the AddHyperlink sub to put in the hyperlinks.
Use the Worksheet_Followhyperlink event to get the row for the info and to call the SendEmail macro.

Code to shell to Thunderbird found here:
How can I automatically send email from Thunderbird with Excel VBA? - Stack Overflow

Hyperlink to run macro found here:
Link Hyperlink to Excel Macro — Excel Dashboards VBA and more

Doc to add hyperlink using code found here:
Hyperlinks.Add method (Excel) | Microsoft Docs

Hope this helps.

Attached Files

Email_using_Thunderbird.xlsm (18.4 KB, 628 views)