I have the same Problem with Seblod and J 3.5.1. No Mails are send. I have many sites using Seblod which I updated tu 3.5.1 :( . I get the Error "0 - Invalid address" after submitting Forms. Any suggestions about a solution?
Based solution on the forum joomla, which could be implemented in the email field SEBLOD ... /plugins/cck_field/email/email.php
Report on JMail class and one addReplyTo array (array ($ replyTo, $ replyToName))
http://forum.joomla.org/viewtopic.php?f=708&t=917253&p=3386537#p3386640
Some help!!!