My goodness, what fortuitous timing.  I'd been thinking about asking about this very thing.

Besides parsing HTML and working with datetimes, the most frequent question in php seems to be about the mail function.  For the uninitiated, the built-in mailing function is terribly unreliable and provides no feedback when things go wrong.  Combine this with the average quality of shared hosting, and it's no wonder why we get so many questions about sending mail through PHP.

Thankfully there is a known, finite set of solutions to these mailing problems. Many are solved by the various anti-spam techniques documented on Jeff Atwood's well-known blog post about mail deliverability.  Many are solved by using one of a handful of modern third-party mailing libraries instead of the built-in function.

Because there are so many duplicates, it's hard to actually find a good enough duplicate to suggest a closure.  So I was thinking that writing a definitive guide covering the most frequent problems might serve a worthwhile purpose.

Such things have been tried before, like "Reference - What does this symbol mean in PHP?", but with mixed success.

I think that spreading the word that such a resource exists might be problematic, followed closely by making sure that questions actually get closed as duplicates when they fit the pattern.  While knowledge would spread slowly throughout frequent contributors, I'm actually far more worried about dupe closures.  Some users don't care for having their questions closed as dupes, and some users think that they are special snowflakes that are totally asking a different question for which the answer is still the same.  (The answer being that mail() sucks and you shouldn't use it except as a last resort.)

Would a meta-answer be a good idea?
I'm wondering if the need to alter the indentation of code to adjust the nesting has any adverse effects on merging changes in a system like SVN.

This is a really open ended question. I'm sort of fishing for information/anecdotes here.

Edit: Thanks all! I'd accept an answer but which one? I up moded them all.
