The solution for handling

<br />

tags within headlines is actually quite simple. Essentially, those tags are only there for display purposes on the site itself (in this case, on Copyblogger), and we really don’t want them to affect the presentation in any other areas where headlines may be displayed.

Within the site itself, headlines appear on the [1] front page, on [2] individual post pages, at the bottom of individual post pages in the form of [3] inter-postal links, and in lists of [4] related posts that follow individual posts.

In cases [3] and [4] from the previous paragraph, all I had to do was add in some very simple CSS to suppress the

<br />

tags, which have been added in the title field of the post entry page (within WordPress).

I use the rule of specificity to target the headlines, and a CSS declaration to “turn off” the

<br />

tags, like so:

ul#related_posts li br { display: none; }

The above declaration prevents all

<br />

tags from displaying, but only if they lie within the li elements of an unordered list whose ID is “related_posts”.

As far as feed readers go, I don’t have any direct control over the display of

<br />

tags there. Despite that, I suspect that popular readers like Google Reader and Bloglines suppress

<br />

tags within headlines. It would make sense to do so, simply because one of the major challenges these readers face is to present a unified interface that features content from a zillion different sites, each of which probably has a unique way of formatting and organizing content.

There’s not an API call to check that but what you can do (and what we do on our blog) is to integrate Google Analytics so that your source is tagged as “email” (your readers may also find Google’s URL builder helpful).

It makes a strategic decision for me a lot easier.

You didn’t mention the possibility of reporting feed subscription numbers to Feedburner. They are getting part of the numbers probably anyway based upon open rate with included images, but it would be good to have the full data being fed. I think it only requires reporting to in headers each time to fetch a feed.

The feedburner data is important both for social proof and revenue.

As for tips, whilst some of my readers will no doubt appreciate that, many are very advanced.

As an example, is there a way I can check via some kind of an API call as to whether a visitor is an email subscriber, or do I just have to do it with cookies?

I think it would be easier to just modify a theme, and use a custom field if it is set, otherwise use the_title.

The RSS feeds would still use the_title by default.

What precisely do you want to do? Insert a break only when the post appears at the blog, but otherwise, keep it out?