MailAddress accepts invalid email address with consecutive dots #109590
Description
Description
According to RFC5322/RFC2822, email addresses with multiple consecutive dots are invalid, e.g. test..address@example.com or address@test..example.com should be rejected when parsing email addresses.
Quoted from https://serverfault.com/questions/395766/are-two-periods-allowed-in-the-local-part-of-an-email-address:
RFC 2822 seems to object to this in section 3.4.1:
The locally interpreted string is either a quoted-string or a dot-atom. If the string can be represented as a dot-atom (that is, it contains no characters other than atext characters or "." surrounded by atext characters), then the dot-atom form SHOULD be used and the quoted-string form SHOULD NOT be used. Comments and folding white space SHOULD NOT be used around the "@" in the addr-spec.
Furthermore, in that same section, it references this:
addr-spec = local-part "@" domain
local-part = dot-atom / quoted-string / obs-local-part
Reproduction Steps
public class Program
{
public static void Main(string[] args)
{
Console.WriteLine(new System.Net.Mail.MailAddress("test..address@example.it"));
Console.WriteLine(new System.Net.Mail.MailAddress("address@test..example.it"));
}
}
Expected behavior
Invalid addresses should be rejected by the MailAddress class.
Actual behavior
Currently the System.Net.Mail.MailAddress class happily accepts such malformed addresses.
Regression?
Tested on .net 4.7.2, .net 6 and 8, behavior is the same so I'd say not a regression.
Known Workarounds
Manual validation or using any other tool to validate addresses before passing them to MailAddress. For example, MimeKit throws an exception with both two lines:
Console.WriteLine(MailboxAddress.Parse("test..address@example.it"));
Console.WriteLine(MailboxAddress.Parse("address@test..example.it"));
Configuration
Tested on .net 4.7.2, .net 6 and .net 8.
Other information
No response