Syntax checking on e-mail addresses

You can use the following code to validate e-mail addresses in your Foxpro applications.

* Procedure validatemail([emailaddress])

PARAMETERS pEmail

LOCAL cDomains, cPiece, cMessage, cNum, lDomain, lemailname

pEmail = LOWER(ALLTRIM(pEmail))
cMessage = ""
lDomain = .t.
lEmailname = .t.

IF !EMPTY(pEmail)

cdomains = '"aero", "asia", "biz", "cat", "com", "coop", ' +;
'"edu", "gov", "info", "int", "jobs", "mil", "mobi", "museum", ' +;
'"name", "net", "org", "pro", "tel", "travel"'

* some extra checks which are not tackled below
IF ".." $ pemail OR "@." $ pemail OR ".@" $ pemail && missing pieces between dots and pigtail
lEmailname = .f.
ENDIF
IF NOT "@" $ pEmail && no pigtail
lEmailname = .f.
ENDIF
IF OCCURS("@", pemail) > 1 && multiple pigtails
lEmailname = .f.
ENDIF

* check the emailname
cPiece = LEFT(pEmail, AT("@", pEmail)-1)
IF EMPTY(cPiece)
lEmailname = .f.
ELSE
FOR i = 1 TO LEN(cPiece)
cNum = ASC(SUBSTR(cPiece,i,1))
* A to Z, 0 to 9, ! to /
IF between(cNum, 97,122) OR;
between(cNum, 48,57) OR;
between(cNum, 33,47)
ELSE
lEmailname = .f.
ENDIF
ENDFOR
ENDIF

* check the domain name
cPiece = SUBSTR(pEmail, RAT("@", pEmail)+1)
IF EMPTY(cPiece) && empty
lDomain = .f.
ELSE
IF LEN(cPiece) < 4 && domain name to short
lDomain = .f.
ENDIF

cPiece = SUBSTR(pEmail, RAT(".", pEmail)+1)
IF LEN(cPiece) < 2 && part after the last dot to short
lDomain = .f.
ENDIF
IF LEFT(pEmail,1) $ "." && begins with a dot
lDomain = .f.
ENDIF

FOR i = 1 TO LEN(cPiece)
cNum = ASC(SUBSTR(cPiece,i,1))
* A to Z, 0 to 9, ! to /
IF between(cNum, 97,122) OR;
between(cNum, 48,57) OR;
between(cNum, 33,47)
ELSE
lDomain = .f.
ENDIF
ENDFOR

IF LEN(cPiece) > 2 && top level domain
IF NOT '"' + cPiece + '"' $ cdomains && no top level domain
lDomain = .f.
ENDIF
ELSE
* If you have a list with all the country codes, you could check them here...
ENDIF
ENDIF
ENDIF

RETURN (lEmailname = .T. AND lDomain = .T.)