This is subjective, but I would not use any line breaks at all (when you say "line break" in the context of a VF email, I think of the break row tag <br />
, so correct me if that's not the case) and just use paragraph (<p>
) tags to wrap text together. Then, if you have any text that absolutely needs a hard return before and/or after it, it similarly gets wrapped in <p>
tags.
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Velit ut tortor pretium viverra suspendisse potenti.</p>
<p>
<strong>Important sentence with its own line (or paragraph, screen depending)</strong>
</p>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit...</p>
Think about what your users can receive emails on: phones, tablets, tiny laptops, big desktop monitors, in a full-screen window, in a side column in Outlook. If you just use paragraphs, the text will flow naturally and fit the window that the user is currently looking at. If you open a long-winded email in your mail client right now and stretch it out, I would bet that the text will accommodate the full-width. Most people don't consider how long the lines are and they just type until their message is done.
There are some considerations to be made regarding the length of a line of text for readability (generally considered to be 50-60 characters per line) that many websites and marketing emails will take into account in their design. Take StackExchange for instance. When you look at this page most of the content is confined to a div that is no wider than 1100px
. That is by design so that text doesn't trail all the way across a screen, unless the screen is sufficiently small like on a phone. There are a lot of great resources on typography and layouts you can find on this subject so I won't go into it any further here as it is outside the scope of this site.