More explanation of untrusted_set_sender.

1 files changed, 1 insertions, 1 deletions

diff --git a/docs/installing/email.md b/docs/installing/email.md
index 87915315f..54f6d0c76 100644
--- a/docs/installing/email.md
+++ b/docs/installing/email.md
@@ -148,7 +148,7 @@ Create `/etc/exim4/conf.d/main/04_alaveteli_options` with the command:
 
 This sets up `ALAVETELI_HOME` and `ALAVETELI_USER` for use in other config files, and sets up logging. The `ALAVETELI_HOME` variable should be set to the directory where Alaveteli is installed. `ALAVETELI_USER` should be the Unix user that is going to run your site. They should have write permissions on `ALAVETELI_HOME`.
 
-Note that if you are editing an existing exim config that restricts the `untrusted_set_sender` option, you will need also to add `ALAVETELI_USER` to the `trusted_users` list in order to allow them to set the return path on outgoing mail. This option is in `/etx/exim4/conf.d/main/02_exim4-config_options` in a split config.
+Note: If you are editing an existing exim config rather than creating a new one, check the `untrusted_set_sender` option in  `/etc/exim4/conf.d/main/02_exim4-config_options`. By default, untrusted users in exim are only allowed to set an empty envelope sender address, to declare that a message should never generate any bounces. `untrusted_set_sender` can be set to a list of address patterns, meaning that  untrusted users are allowed to set envelope sender addresses that match any of the patterns in the list. If a pattern list is specified,  you will need also to add `ALAVETELI_USER` to the `trusted_users` list in order to allow them to set the return path on outgoing mail. This option is also in `/etc/exim4/conf.d/main/02_exim4-config_options` in a split config. If `untrusted_set_sender` is set to `*`, that means that untrusted users can set envelope sender addresses without restriction, so there's no need to add `ALAVETELI_USER` to the `trusted_users` list.
 
 The name and location of the log files created by Exim must match what the
 `load-mail-server-logs` script expects, which is why you must provide the