You appear to have two issues with your log shipping configuration.
The first is the SQL Server Error (4326), which relates to log backups being out of sequence.
If you look in your SQL Backup logging directory (by default, this is at c:\\documents and settings\\all users\\application data\\red gate\\sql backup\\log\\<instance name>), you should find a timestamped log that corresponds to the restore in question.
This log should give you information on what was wrong with the restore, and you can find which files in your "backups" directory you need to copy to the network share (or need to move from the network share to the "processed" directory). The log shipping should then start functioning correctly.
The second issue you appear to have is the SQL Backup Warning 150, which is because you haven't configured a SMTP mail server in the SQL Backup 4.6 User Interface.
If you open the "Options" dialog, and select the SQL Server instance(s) you are working with, you can enter a SMTP mail server, and this particular warning should then go away.
Ideally you should be entering an SMTP server name on both the SQL Server instances used for log shipping.
If you need any more information or detailed help with your question, feel free to follow-up on the forum or drop me an email.
Hope that helps,