I recently installed LimeSurvey on a server running Ubuntu 18.4 and PHP 7.2. We are using limesurvey3.15.1. Everything seems to be working, except when I go to send the invitations. When I do so, it completely locks the web server. I have to either wait for it to time out, or restart Apache.

The mail server is Office 365. I have attached images of my mail settings.

The thing is that I was able to get this all to work several months ago on a different server with the same configuration and the same e-mail account. So I'm just missing something here. Any help would be appreciated.

mcrockett wrote: Everything seems to be working, except when I go to send the invitations. When I do so, it completely locks the web server.

The lockup might be an indication for an communication block (e.g firewall), which prevents the webserver to connect to the ports at office365.

You might activate debugmodes in LimeSurvey or LimeSurvey mail debug to get more infos.
In your screenshot you have SMTP debug mode on.
The person who setup the webserver/php might help as well.

As stated originally, I had this working several months ago on a server with a similar setup, using the same e-mail account in Office 365. So I know that there is nothing blocking in Office 365.

Yes, SMTP debug mode is on, but it locks before I get any output, unless there's a log file somewhere that I'm supposed to check.

I got this figured out. I had failed to put the port numbers. All seems to be working now. But thank you for your attention and your reply.