After some discussion, I have come across a rather complicated situation. Say I intend to display an email address. I have, obviously, limited space available on the screen - be that browser or application UI. Email addresses are, however, limited to 64 + 1 + 255 = 320 characters by RFC5321, while the same RFC also caps the path at 256 (which leads to an actual 254) characters. That's quite a lot for most screens - the lines I'm writing right now contain less than a hundred characters each.
So, that poses a bit of a problem when trying to display email addresses. At this character count, sufficiently large containers would seem huge for a "default-sized" email address (my average is a bit below 30 characters right now), while a smaller container would lead to overflow.
At first the option to use a smaller container but introduce line-breaks on longer addresses seems like a good idea.
Which brings me to the first important question to this: Where do I break? After a set/relative amount of characters? Before or after the
And the second question follows right after: How do I break? Zero-width space?
<wbr> in HTML? Insert a dash or not?
There seem to be reasons for and against any of these, but I can't for the life of me find any sources to go off in my decision. It seems as though nobody ever actually dealt with this situation (that is, the physical cap on estate is never exhausted). The best I can find are some online publishing styleguides preferring an email address in one line and adjusting surrounding elements to make that work. Well, we might just not have that option under some circumstances.