In 6.2.2 we are not seeing email alerts being sent out.
Searching the logs I see:
ERROR sendemail:348 - 'NoneType' object has no attribute 'find' while sending mail to: email@example.com
ERROR sendemail:112 - Sending email. subject="blah blah"
You can also consult the python log file by looking for this source in the internal index- $SPLUNK_HOME/var/log/splunk/python.log
This will show INFO and ERROR messages emitted by the email script and may show more information for troubleshooting. There can be a number of root causes, like SMTP be down, queued, etc related to sending mail. You need to look at the log and see.
Usually it is some problem with sendmail.
Did you check the python.log source too, usually that does yield other clues, like this one showing diskspace being exhausted:
/opt/splunk/var/log/splunk/python.log.1:2014-06-19 17:41:10,702 -0400 ERROR sendemail:112 - Sending email. subject
/opt/splunk/var/log/splunk/python.log.1:2014-06-19 17:41:10,702 -0400 ERROR sendemail:348 - (452, '4.4.5 Insufficient disk space; try again later', firstname.lastname@example.org') while sending mail to: email@example.com
This will show any possible errors. If you are in linux, you can also check /var/log/maillog
The first error is a common python error. the script that sends the email for an alert is written in python.
Looking at v 6.2.2 of this script, this error is emitted when the script tries to transmit the email. There should be another error message immediately before the one shown in that same index.
You can also consult the file - $SPLUNK_HOME/var/log/splunk/python.log
This will show INFO and ERROR messages emitted by the email script. It will likely yield further clues.
Inspect your mail server configuration under Settings->Server Settings->Email Settings