Copy fitting is a feature that will automatically shrink text by reducing the font size, when there is more text than the text box can hold. The font size will be reduced to the font size needed to fit the text in the text box. However, text will not be shrunk beyond the specified minimum font size. When the text needs to be resized, all text will be resized step by step until the text fits or the minimum font size is reached.

Minimum font size: When Copy Fitting is enable, the minimum size the font can reach is 1, by default the minimum font size is 8.
Allow line breaks is a feature which automatically replaces some of the blank spaces between words by line breaks, in a way that each line fits in the viewable window. In PrintShop Mail "Allow line breaks" is set to Yes by default.

When Copy Fitting is set to "Yes", individual words can be broken due to word wrap.

When Copy Fitting is set to "No", text only fit if the individual words are not broken. Text will break on spaces only.
Note:Copy Fitting is not allowed for linked objects.