At the time of project installation we put version here.
And same put on dashboard file as well as said in above reply.
Most of the things already fixed in given points and some will of them will be add fixed in upcoming release.
May be they have not taken latest zip from our official website https://www.uvdesk.com/en/opensource/
open dashboard.html.twig and update here.
Locate the file vendor->uvdesk->core-framework->Services->EmailService.php.
Open the EmailService.php reach to sendMail() function.
and dump() the exception as in attached images.
It will show the error you are facing while sending mails (if adding an agent, creating a ticket etc).
Other helpful link:
For Gmail Do below things first:
Enable less secure app for gmail: https://myaccount.google.com/lesssecureapps
Please enable this also: https://accounts.google.com/b/0/DisplayUnlockCaptcha
If you have setup it on sever then you can send us the helpdesk link along with login details of admin panel we will check.
you can mail us firstname.lastname@example.org here for this.
Also mention which version of uvdesk opensource you are using ?
Do you want to notify to any admin or any agent if a new ticket comes.?