please unblock my maxbulk mailer

[HydroPeter]

I bought maxbulk mailer a few years ago.
I clicked the free upgrade button. & installed the latest
entered my registration code and maxbulk refused to load my mbm email
I uninstalled the latest.
installed an earlier version and I could edit my email
but when I come to send I get a red ! with the text in red
503 50.0 Need MAIL before RCPT.
Please help.
Peter

 

[stanbusk]

Are you authenticating with your server properly? Have you tried the ESMTP authentication?