I believe we are having the same problem which you had. Have you been able to fix it?
In our last campaign some links in the email where broken and sent us to a link with this message
"Warning: mysqli::mysqli(): Headers and client library minor version mismatch. Headers:50532 Library:50615 in /home/hoytraba/sendy/l.php on line 15
Warning: Cannot modify header information - headers already sent by (output started at /home/hoytraba/sendy/l.php:15) in /home/hoytraba/sendy/l.php on line 167"
We look foward to your response. Thanks for any help!!!