Email address validation does not allow emails with plus sign.

[marisks]

The regex here doesn't allow emails like test+test@example.com which is a valid email: https://github.com/episerver/Quicksilver/blob/master/Sources/EPiServer.Reference.Commerce.Site/Infrastructure/Attributes/LocalizedEmailAttribute.cs

[quanmaiepi]

That's true. However the regex to validate all "valid emails" would look like this

(?:(?:\r\n)?[ \t])(?:(?:(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t] )+|\Z|(?=[["()<>@,;:\".[]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?: \r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:( ?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t])))@(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\0 31]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)\ ](?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+ (?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?: (?:\r\n)?[ \t])))|(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z |(?=[["()<>@,;:\".[]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n) ?[ \t]))\<(?:(?:\r\n)?[ \t])(?:@(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\ r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n) ?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t] )))(?:,@(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t]) )(?:.(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t] )+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t])))) :(?:(?:\r\n)?[ \t]))?(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+ |\Z|(?=[["()<>@,;:\".[]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r \n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?: \r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t ]))"(?:(?:\r\n)?[ \t])))@(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031 ]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)]( ?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(? :(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(? :\r\n)?[ \t])))>(?:(?:\r\n)?[ \t]))|(?:[^()<>@,;:\".[] \000-\031]+(?:(? :(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)? [ \t]))"(?:(?:\r\n)?[ \t])):(?:(?:\r\n)?[ \t])(?:(?:(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|"(?:[^\"\r\]| \.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[^()<> @,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|" (?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t])))@(?:(?:\r\n)?[ \t] )(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\ ".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(? :[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[ ]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t])))|(?:[^()<>@,;:\".[] \000- \031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|"(?:[^\"\r\]|\.|( ?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t]))\<(?:(?:\r\n)?[ \t])(?:@(?:[^()<>@,; :\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([ ^[]\r\]|\.)](?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\" .[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[\ ]\r\]|\.)](?:(?:\r\n)?[ \t])))(?:,@(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".\ [] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\ r\]|\.)](?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\] |\.)](?:(?:\r\n)?[ \t])))):(?:(?:\r\n)?[ \t]))?(?:[^()<>@,;:\".[] \0 00-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|"(?:[^\"\r\]|\ .|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[^()<>@, ;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[]]))|"(? :[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t])))@(?:(?:\r\n)?[ \t]) (?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\". []]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t])(?:[ ^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[] ]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t])))>(?:(?:\r\n)?[ \t]))(?:,\s( ?:(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\ ".[]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t]))(?:.(?:( ?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[ ["()<>@,;:\".[]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t ])))@(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t ])+|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t]))(? :.(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+| \Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t])))|(?: [^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\".[\ ]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t]))\<(?:(?:\r\n) ?[ \t])(?:@(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[[" ()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n) ?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<> @,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t])))(?:,@(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@, ;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t]))(?:.(?:(?:\r\n)?[ \t] )(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\ ".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t])))):(?:(?:\r\n)?[ \t]))? (?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[["()<>@,;:\". []]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t]))(?:.(?:(?: \r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[[ "()<>@,;:\".[]]))|"(?:[^\"\r\]|\.|(?:(?:\r\n)?[ \t]))"(?:(?:\r\n)?[ \t]) ))@(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t]) +|\Z|(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t]))(?:\ .(?:(?:\r\n)?[ \t])(?:[^()<>@,;:\".[] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z |(?=[["()<>@,;:\".[]]))|[([^[]\r\]|\.)](?:(?:\r\n)?[ \t])))>(?:( ?:\r\n)?[ \t]))))?;\s)

It's pretty much an implementation detail. I think if you want to allow test+test@example.com it would be fairly easy to do. We just want to show the basics, and then you can extend as much as you want.

[marisks]

The plus signs are very common. Many payment providers use those for testing purposes. As Quicksilver is used to demo different technologies based on Episerver, it would be just wise to allow "plus" signs too. Anyway, it is better to be less strict to email validation than too strict and getting rid of lot of customers :)

This regex is working well for me: https://stackoverflow.com/a/5503271/660154 But I haven't tested it on many emails.