If you don't supply a fallback term and there's no data to show from a personalisation tag, a space will be inserted. This can create unintended sentence structure issues. For example:
Hey [firstname,fallback=], check out our VIP offer!
If there's no recipient name and no fallback term, the sentence above will look like this:
Hey , check out our VIP offer!
Another example:
Come to our store opening, [firstname,fallback=]!
No recipient name and no fallback term will result in this:
Come to our store opening, !
There are two ways you can solve this: