^\d{6}$
^\d{6}\.\d{3}$


are the correct patterns you can test them 6 digits only and 6 digits dot 3 digits.

^\d{6}((\.\d{3}$)|$)


will match either 6 digits or 6 digits dot 3 digits

Rubular is your friend!

Regular Expression to Match String Exactly?
I want to give another person the ability to send emails in my name. This person should be able to send mail using my email address, but not be able to read my email.

Does anybody know a webapp or application that can do this?

I use gmail, but am willing to try others.
