Depending on the format you have chosen you will be able to format your text in different ways:

Plain Text
The Plain Text format only includes text alignment tools to center, justify, right align and rewrap your text along with the possibility to remove styles if present using default font and size. All that is done using the corresponding menus from the Format top menu, Rewrap Text, Align to Right, Align to Center, Justify and Make Plain Text or the alignment buttons located on the left above the message field.

As this is Plain Text format, the center, justify and right alignments are performed inserting spaces inside the text. The Rewrap Text function not only left align but set all lines to 72 characters long removing all inserted spaces as well. You can remove styles using the message contextual menu 'Make Plain Text' or the shift+cmd+T shortcut as well.

Styled Text
The Styled Text format lets you use real right, left and center alignment and a wide range of rich formatting options like different fonts, colors and sizes using bold, Italic and Underline. All the formatting options are accessible both from the formatting toolbar placed right above the message field and the Format top menu.

The formatting toolbar also lets you create normal, definition and bullet lists and change the message background color.

Note that Styled Text format is converted to HTML code at delivery time so you can use standard HTML tags inside your message as well. They will be passed thru to the final message so for example, to justify your text you can simply do the following:

<div align="Justify">
Your justified text here.
</div>

Furthermore, you can do tables to display text formatted into columns. Just create the table with your favorite HTML editor and paste the code to the message removing all line breaks. It looks like this:

<table><tr><td>Product</td><td>Price</td></tr><tr><td>eMail Verifier</td><td>$24.90</td></tr><tr><td>eMail Extractor</td><td>$16.90</td></tr></table>

Anyway it is recommend you send a test message to yourself to check if the message looks like as expected before sending to your recipient list.