Add basic/generic email validator logic

for use mostly in non-web scenarios, probably

tailbone/util.py

@@ -2,7 +2,7 @@
 ################################################################################
 #
 #  Rattail -- Retail Software Framework
-#  Copyright © 2010-2018 Lance Edgar
+#  Copyright © 2010-2019 Lance Edgar
 #
 #  This file is part of Rattail.
 #
@@ -35,6 +35,7 @@ import humanize
 from rattail.time import timezone, make_utc
 from rattail.files import resource_path
 
+import colander
 from pyramid.renderers import get_renderer
 from webhelpers2.html import HTML, tags
 
@@ -175,3 +176,25 @@ def get_effective_theme(rattail_config, theme=None, session=None):
         raise ValueError("theme not available: {}".format(theme))
 
     return theme
+
+
+def validate_email_address(address):
+    """
+    Perform basic validation on the given email address.  This leverages the
+    ``colander`` package for actual validation logic.
+    """
+    node = colander.SchemaNode(typ=colander.String)
+    validator = colander.Email()
+    validator(node, address)
+    return address
+
+
+def email_address_is_valid(address):
+    """
+    Returns boolean indicating whether the address can validate.
+    """
+    try:
+        validate_email_address(address)
+    except colander.Invalid:
+        return False
+    return True