[rt-users] no alert for invalid mail addresses

[Jeffrey Pilant]

Petr Hanousek writes:
>Hi geeks,
>sometimes someone here mistypes the mail address of Requestor or CC. The
>typos in addresses are various, my question is about the really obvious
>ones. Like if you put to CC an address "a at b". Is there any mechanism in
>RT to detect such mistakes and say something at least? Or can I have a
>feature request for this? :)
>
>If you try this in Gmail or Thunderbird, an error is raised and the
>message is not sent.

Check out
	http://www.regular-expressions.info/email.html
It indicates the 'most' official regex is:
\A(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*
 |  "(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]
      |  \\[\x01-\x09\x0b\x0c\x0e-\x7f])*")
@ (?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?
  |  \[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}
       (?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:
          (?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]
          |  \\[\x01-\x09\x0b\x0c\x0e-\x7f])+)
     \])\z

Yeah.  Quite a mouthful.  This is because there are quite a few ways to express email addresses.  And even this is not foolproof.

The same page also has other simpler regex expressions that work a fair amount of the time, but are less complicated, like:
\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b

The page claims it is 99% effective.

That, however, does not solve your problem.  Just because it is formulated correctly does not mean it is a valid address.

The usual solution is to whitelist the addresses and do a lookup.  Any address not found gets added tentatively, but flagged for testing.  You can also at this time prompt for acceptance vs. going back to an edit screen.  This does require you maintain a list of valid email addresses somewhere.  The user list is a likely place, but if you are sending emails to people who are not users, then that fails.

/jeff
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