The following pseudocode algorithm attempts to check whether a string is a valid email address. FUNCTION IsValid(InString : STRING) RETURNS BOOLEAN DECLARE Index, Dots, Ats, Others : INTEGER DECLARE NextChar : CHAR DECLARE Valid : BOOLEAN Index <- 1 Dots <- 0 Ats <- 0 Others <- 0 Valid <- TRUE REPEAT NextChar <- MID(InString, Index, 1) CASE OF NextChar '.' : Dots <- Dots + 1 '@' : Ats <- Ats + 1 IF Ats > 1 THEN Valid <- FALSE ENDIF OTHERWISE : Others <- Others + 1 ENDCASE IF Dots > 1 AND Ats = 0 THEN Valid <- FALSE ELSE Index <- Index + 1 ENDIF UNTIL Index > LENGTH(InString) OR Valid = FALSE IF NOT (Dots >= 1 AND Ats = 1 AND Others > 8) THEN Valid <- FALSE ENDIF RETURN Valid ENDFUNCTION