Php code for validating email address
A valid email is of the format: [email protected] The name can be a set of ‘atoms’ separated by dots. single or double quotes and any character inside the quotes Now, to the domain part. MUSEUM .travel, .international or even .vermögensberatung For example all the following email addresses are valid: Source The sad truth is that despite the complex regular expression validation, the email may not be existing, so can still be invalid for practical purposes.Most email validation checks assumes that the top level domain can have up to 4 characters. You have just validated the format – not its existence.
in the domain part, a comment in the source code (in ext/filter/logical_filters.c) justifies this rejection thus: * The regex below is based on a regex by Michael Rushton. I changed it to only consider routeable * addresses as valid.
Michael's regex considers [email protected] a valid address * which conflicts with section 2.3.5 of RFC 5321 which states that: * * Only resolvable, fully-qualified domain names (FQDNs) are permitted * when domain names are used in SMTP.
In other words, names that can * be resolved to MX RRs or address (i.e., A or AAAA) RRs (as discussed * in Section 5) are permitted, as are CNAME RRs whose targets can be * resolved, in turn, to MX or address RRs.
Since there are real, live IDNs on the Internet, that means the filtered output is too strict, leading to false negatives.
Punycode-encoded IDN addresses pass the filter correctly; so before checking for validity, it is necessary to convert the e-mail address to punycode.