ensure emails are formatted before sending

we allow some invalid to addresses - for example, phone numbers with
spaces or brackets - in the database. This is so that users can match
up their data in a format that they expect (since they passed it in).
When we send SMS, we strip this formatting just before sending - but we
weren't with email. This commit changes that and adds some tests.

It also adds formatting for reply_to addresses. We should never expect
invalid reply_to email addresses in our data, but just in case, lets
validate them here.

Also, bump requirements.txt to capture some more email validation

app/delivery/send_to_providers.py

@@ -3,7 +3,8 @@ from datetime import datetime
 
 from flask import current_app
 from notifications_utils.recipients import (
-    validate_and_format_phone_number
+    validate_and_format_phone_number,
+    validate_and_format_email_address
 )
 from notifications_utils.template import HTMLEmailTemplate, PlainTextEmailTemplate, SMSMessageTemplate
 
@@ -130,11 +131,11 @@ def send_email_to_provider(notification):
 
             reference = provider.send_email(
                 from_address,
-                notification.to,
+                validate_and_format_email_address(notification.to),
                 plain_text_email.subject,
                 body=str(plain_text_email),
                 html_body=str(html_email),
-                reply_to_address=email_reply_to,
+                reply_to_address=validate_and_format_email_address(email_reply_to) if email_reply_to else None,
             )
             notification.reference = reference
             update_notification(notification, provider)