Merge pull request #3455 from edx/usman/lms1466-email-formatting

Wraps long lines in bulk email messages.

common/lib/mail_utils.py

@@ -0,0 +1,22 @@
+"""
+Utilities related to mailing.
+"""
+
+import textwrap
+
+MAX_LINE_LENGTH = 900
+
+
+def wrap_message(message, width=MAX_LINE_LENGTH):
+    """
+    RFC 2822 states that line lengths in emails must be less than 998. Some MTA's add newlines to messages if any line
+    exceeds a certain limit (the exact limit varies). Sendmail goes so far as to add '!\n' after the 990th character in
+    a line. To ensure that messages look consistent this helper function wraps long lines to a conservative length.
+    """
+    lines = message.split('\n')
+    wrapped_lines = [textwrap.fill(
+        line, width, expand_tabs=False, replace_whitespace=False, drop_whitespace=False, break_on_hyphens=False
+    ) for line in lines]
+    wrapped_message = '\n'.join(wrapped_lines)
+
+    return wrapped_message