Emails are truncated when Combine multiple alerts into summary notification is checked for an alert.
This issue is due to a limitation in the size of the body of email when email is sent via SharePoint.
1. The farm account running the SharePoint Timer service in Administrative Tools > Services (OWSTIMER.svc) can be configured to have a mail box in the Exchange server.
2. Once the email is setup, then go to the Alert+ Configuration list, and for the alert(s) in question, edit the alert(s), and change the Mail Sender Typedrop down to use MailMessage.
Note: by default that field will be blank or will have SharePoint selected (if it is blank, it is using SharePoint).
3. The From email address configured in Central Administration does not need to use this mailbox address. Alert Plus will use the configurable address in the "from" line in the email sent by the system.
If you do not wish to monitor the farm account mail box address, then you can forward replies to a mailing list that includes all SharePoint administrators, or configure the From email address in Central Administration to use a different address.