After evaluating this plugin I had a view problems, all due my fantastic computing anti-talent capabilities, but I must say these where quickly rectified by the near immediate response from http://xyzscripts.com/
As everything worked as advertised, and easy to setup, I had no hesitation to upgrade to the Pro edition with the enhanced capabilities - again all working as advertised.
A further reason for choosing this plugin is that you do not have to pay a third party to do your mailing, it all happens from the server of your host. By being able to to send via the SMTP server, emails are authenticated by SPF and DKIM and less likely to fill the spam folder.
(the only small drawback that this plugin has is that it cannot harvest the registered subscribers of a website into a mailing list. As I wanted to mail all the registered users and give them the option to unsubscribe from future mailings, I first had to download the user addresses and then import them back into Newsletter Manager - possibly a self populating mail list from registered users is an upgrade worth thinking about)
Thanks and regards
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