The page for that add-on shows Works with Thunderbird 3.0 - 12.* with the last update being Sept. 19, 2011 https://addons.thunderbird.net/en-US/thunderbird/addon/tms-bulk-sms/

It also says it only works with South African mobile networks. Just a guess, but I doubt you are in South Africa.

Despite many folks thinking otherwise. SMS or Short message Service is not in any way related to email. It is a service that is phone number based and designed for mobile/cell usage.

So to link an email address you need a provider for your SMS. Normally this is your phone provider, and some do offer email to SMS bridges.

For instance on provider of email to SMS services here in Australia where I am is https://www.clicksend.com/au/pricing/au/ and they charge 7c per message sent.

Wikipedia has a list of some US and Canadian providers details https://en.wikipedia.org/wiki/SMS_gateway I have no idea as to the accuracy of the list of the current status of any of the services.

If you know the recipient's 'SMS gateway address', an email can be sent that is received as a text:

https://www.makeuseof.com/tag/email-to-sms/

For example, if the recipient is an AT&T customer, send to [email protected], where 12... is their phone number.

Ok , great info Thanks All