Free Webmail Username Restrictions
What criteria determine a valid username for the top web mail providers? This seems like it would be useful for filtering that list of a couple hundred thousand e-mail addresses we’ve all got lying around.
Yahoo! Mail Basic Restrictions (yahoo.com, ymail.com, rocketmail.com):
- 4 to 32 characters
- Starts with a letter
- Letters, numbers, underscores and one period (.)
- No consecutive underscores or period, or combination of the two ([_.]{2}
- Cannot end with underscore or period
Regex for invalid username:
(?:^.{,3}$|^.{33,}$|^[^a-z]|[^a-z0-9_.]|\..*\.|[_.]{2}|[_.]$)
Gmail Basic Restrictions (gmail.com):
- 6 to 30 characters
- Only letters, numbers and periods
- Starts and ends alphanumeric
- No consecutive periods (also required by RFC 2822)
Because of the restriction on the character set (#2), RFC 2822 compliance guarantees #3 & #4. As such, these won’t appear in the following regex.
Regex for invalid username:
(?:^.{,5}$|^.{31,}$|[^a-z0-9.])
Windows Live Restrictions (hotmail.com, live.com):
- 4 to 32 characters
- Only letters, numbers, periods, hyphens and underscores
- Cannot have the character sequence “fuck”
- Starts with alphanumeric
- Cannot end with a period (also required by RFC 2822)
The minimum length was just a guess on my part. It’s not published, but 4 is the smallest free user name I could find. I’m sure there are words besides “fuck” that aren’t allowed, but you get the point
(?:^.{,3}$|^.{31,}$|[^a-z0-9._-]|fuck|^[^a-z0-9])
MobileMe Restrictions (me.com, mac.com):
- 3 to 20 characters
- Only letters, numbers, periods, hyphens and underscores
Note: The regex on this page are intended for case-insensitive, un-anchored searches.
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webmail naming conventions | AccessAdp.com
2014-05-11 at 05:59