Merge pull request #228 from alphagov/update-send-a-file-by-email

Update guidance for length of time files are available

DOCUMENTATION.md

@@ -314,10 +314,13 @@ with open('file.pdf', 'rb') as f:
 
 Set the number of weeks you want the file to be available using the `retention_period` key.
 
-You can choose any value between 1 week and 78 weeks.
-
 To use this feature will need version 6.4.0 of the Python client library, or a more recent version.
 
+You can choose any value between 1 week and 78 weeks. When deciding this, you should consider:
+
+* the need to protect the recipient’s personal information
+* whether the recipient will need to download the file again later
+
 If you do not choose a value, the file will be available for the default period of 26 weeks (6 months).
 
 Files sent before 12 April 2023 had a longer default period of 78 weeks (18 months).