[geary] Validate entered email address before allowing add a new account.

[Michael Gratton <mjog src gnome org>]

commit 11d093bee2528706bb54f43a06d46c627195d2f1
Author: Michael James Gratton <mike vee net>
Date:   Thu Feb 23 14:23:52 2017 +1100

    Validate entered email address before allowing add a new account.
    
    Bug 775513.

 src/client/accounts/add-edit-page.vala |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/src/client/accounts/add-edit-page.vala b/src/client/accounts/add-edit-page.vala
index a4b53b3..ce06c93 100644
--- a/src/client/accounts/add-edit-page.vala
+++ b/src/client/accounts/add-edit-page.vala
@@ -615,10 +615,14 @@ public class AddEditPage : Gtk.Box {
     }
     
     public bool is_complete() {
+        if (Geary.String.is_empty_or_whitespace(email_address) ||
+            !Geary.RFC822.MailboxAddress.is_valid_address(email_address)) {
+            return false;
+        }
+
         switch (get_service_provider()) {
             case Geary.ServiceProvider.OTHER:
                 if (Geary.String.is_empty_or_whitespace(nickname) ||
-                    Geary.String.is_empty_or_whitespace(email_address) ||
                     Geary.String.is_empty_or_whitespace(imap_host) ||
                     Geary.String.is_empty_or_whitespace(imap_port.to_string()) ||
                     Geary.String.is_empty_or_whitespace(imap_username) ||
@@ -635,7 +639,6 @@ public class AddEditPage : Gtk.Box {
             // GMAIL, YAHOO, and OUTLOOK
             default:
                 if (Geary.String.is_empty_or_whitespace(nickname) ||
-                    Geary.String.is_empty_or_whitespace(email_address) ||
                     Geary.String.is_empty_or_whitespace(password))
                     return false;
             break;