Exchange 2007 valid email address characters

Here are the valid characters for an email address in 2007:

Local Part (before the @ symbol)

• Alphanumeric characters (a-z, A-Z, 0-9)
• Dot (.)
• Hyphen (-)
• Underscore (_)
• Apostrophe (')
• Space ( )

Domain (after the @ symbol)

• Alphanumeric characters (a-z, A-Z, 0-9)
• Dot (.)
• Hyphen (-)
• Underscore (_)

Special characters

• At symbol (@)
• Period (.)
• Plus sign (+)
• Equal sign (=)
• Dollar sign ($)
• Comma (,)
• Colon (:)
• Semicolon (;)
• Less-than sign (<)
• Greater-than sign (>)
• Backslash ()
• Forward slash (/)
• Caret (^)
• Ampersand (&)
• Asterisk (*)
• Parentheses (() and ())
• Brackets ([] and [])
• Braces ({ and })
• Quotation marks ("")
• Apostrophe (')
• Backtick (`)

Length restrictions

• Local part: 64 characters maximum
• Domain: 253 characters maximum
• Total length: 254 characters maximum (including the @ symbol)

Note that these restrictions were in place in 2007, but some email providers may have more relaxed or stricter rules. Additionally, the introduction of Internationalized Domain Names (IDNs) in 2003 allowed for non-ASCII characters in domain names, which expanded the range of valid characters.