Have you actually filled in a valid e-mailadress?

As you sometimes just want to validate some data, and you want to make sure if the user has actually filled in just an emailadres, no other link for example. You can easily validate that using this regexp:
^(([-!#$%&’*+.\/0-9=?A-Z^_`a-z{|}~ ])+@([-!#$%&’*+/0-9=?A-Z^_`a-z{|}~ ]+\.)+[a-zA-Z]{2,6}){0,1}$
The regexp is now optional, you can also require that the user fills someting in(but he can’t leave the item then before filling something in, remember that!):
^(([-!#$%&’*+.\/0-9=?A-Z^_`a-z{|}~ ])+@([-!#$%&’*+/0-9=?A-Z^_`a-z{|}~ ]+\.)+[a-zA-Z]{2,6}){1}$

It’s simple, but usefull… By the way, the emailadres will actually validate emails in the way the RFC-standard is. Altough I won’t validatie adresses like alex@localhost.

If you want to make sure everthing works correctly with all adresses specified in the RFC-standard, use this pattern:

(?:(?:\r\n)?[ \t])*(?:(?:(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:
(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.
|(?:(?:\r\n)?[ \t]))*”(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t]
)*(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=
[\[“()<>@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*”(
?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \
x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\
[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])
*(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[
\[“()<>@,;:\\”.\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*
))*|(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(
?=[\[“()<>@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*
“(?:(?:\r\n)?[ \t])*)*\< (?:(?:\r\n)?[ \t])*(?:@(?:[^()<>@,;:\\”.
\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\
]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?
[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\
Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[
\t])*))*(?:,@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\x1F
]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[\]
\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()
<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@
,;:\\”.\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*)*:(?
:(?:\r\n)?[ \t])*)?(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\
n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.|(?:(?
:\r\n)?[ \t]))*”(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[
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<>@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*”(?:(?:\
r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\x
1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[
\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^
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?:(?:\r\n)?[ \t])*)|(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r
\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.|(?:(
?:\r\n)?[ \t]))*”(?:(?:\r\n)?[ \t])*)*:(?:(?:\r\n)?[ \t])*(?:(?:
(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\
[“()<>@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*”(?:
(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \
x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|”
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(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?
[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(
?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x
00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[
([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*|(?:[^()<>@,;:\\”.\[\]
\x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))
|”(?:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*”(?:(?:\r\n)?[ \t])*)*\< ( ?:(?:\r\n)?[ \t])*(?:@(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:
\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[\]\r\\]|\\.)*
\](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\
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[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\x1F]
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r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*)*:(?:(?:\r\n)?[ \t])*)?(?:[^(
)<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>
@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*”(?:(?:\r\
n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\x
1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|”(?:[^\
“\r\\]|\\.|(?:(?:\r\n)?[ \t]))*”(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\
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F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[\
]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*\>(?:(?:\r\n)?[ \t])*)(?:,\s
*(?:(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(
?=[\[“()<>@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*
“(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[
\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]
))|”(?:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*”(?:(?:\r\n)?[ \t])*))*
@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r
\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[\]\r\\]|\\.)*\]
(?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\
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:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[\]\r\\]|\
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\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*(?:,@(?:(?:\
r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t
])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:\r
\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\
x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\
[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*)*:(?:(?:\r\n)?[ \t])*)?(?
:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[”
()<>@,;:\\”.\[\]]))|”(?:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*”(?:(?
:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x0
0-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|”(?
:[^\”\r\\]|\\.|(?:(?:\r\n)?[ \t]))*”(?:(?:\r\n)?[ \t])*))*@(?:(?
:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00-\x1F]+(?:(?:(?:\r\n)?[
\t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:(?:
\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\”.\[\] \x00
-\x1F]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\[“()<>@,;:\\”.\[\]]))|\[([
^\[\]\r\\]|\\.)*\](?:(?:\r\n)?[ \t])*))*\>(?:(?:\r\n)?[ \t])*))*
)?;\s*)