tchaikovsky wrote:
I haven't been tested yet, but they are many users in my database. I think that I have to send batch by batch of mail invitations with the next button. I thought to modify the script of sending invitations but i don't know which file is located, if you have any tip is appreciated and I promise significant contribution to next LimeSurvey version

When sending invitations/reminder there is a setting to limit the number of emails to be sent during each batch. Using this setting is recommended to avoid emails being classified as spam, see recommendation at this blog post on
www.limesurvey-consulting.com at which I have collected all "spam" related advice I could find at the forums "
How to prevent Limesurvey email invitations or reminders being treated as spam".
If I forgot anything, please add a note here.
Thanks!