Candidate Emails and notifications not sending

Hi all,

I am facing an issue with my candidate emails/notifications in the system, whereby my candidates are not receiving any email notifications.

For example:

When applying for a job via the career site, the candidate are promoted to check their emails for the verification code before being able to apply to the job - however this is not sent to the candidates email address.

I am also facing this issue with the 'Send Message' functionality within the requisition and when inviting candidates to interview.

Has anyone else faced this issue and been able to overcome this?

Please share any help/tips/tricks!