You do not need to use all these techniques in order to validate; instead, choose one or two that feel natural and fitting in a given situation.
Although this seems like a trivial question, I am quite sure it is not :) I need to validate names and surnames of people from all over the world. If it were only English ones I think that this would cut it: I doubt that this is feasible - there are just to much Unicode symbols to exclude all unwanted symbols (and how will tell you what Chinese symbols to exclude?
If they don't properly escape when inserting into SQL, any name with an apostrophe (which your original question already recognizes as necessary) opens you up to security vulnerabilities.
Imagine trying to authenticate a user nameed "Foo'or True Or'foo" — no "dangerous" characters, but there goes your login scheme.
I think that the assumption that every website must accommodate every possible name is fallacious.
Our powerful email validation & verification API is increasing open rates and reducing bounce rates for businesses all over the world.
This section encompasses a variety of mostly verbal techniques. It's a really important aspect in relationships, whether personal, work, or college.
It says FQDNs are permitted, and com, org, or va are (well, may be) valids FQDNs. Some TDLs (although few of them) have MX RRs, the for example "[email protected]" is correct.
The description for FILTER_VALIDATE_URL seems incorrect/misleading. "Beware a valid URL may not specify the HTTP protocol" implies a valid URL cannot specify the HTTP protocol.
If you don't have an SPF record or you want to work on changing yours, great!
Take a look at the SPF record syntax to get a better understanding of what your record means.