Thank you for reaching out to the community forums for help with this. To best be able to assist you, could you let me know what app you are currently using to edit your SMS messages? The default SMS templates provided by Shopify are no longer editable and would require a third party app to customize them.
The standard liquid reference for the store’s contact email would look something like this:
mailto:{{ shop.email }}
The “mailto:” in HTML prompts the device to open their default email app and creates a new email to the email address populated by the shop.email field. I don’t know if this works within SMS messages though.
To include a link in any text message, just type or paste the full URL into your text. Most messaging platforms will automatically turn the URL into a link that allows contacts to click and access the linked page.