You can have a look at the Build Timeout Plug-in [1]. Not sure if you can combine this plug-in with email-ext for notifications, but maybe you can create an internal plug-in for your needs.
Hope that helps,
[1]
https://wiki.jenkins-ci.org/display/JENKINS/Build-timeout+PluginBruno P. Kinoshita
http://kinoshita.eti.brhttp://tupilabs.com>________________________________
> From: Andrey Maraev <
[hidden email]>
>To: jenkinsci-dev <
[hidden email]>
>Sent: Thursday, 3 May 2012 10:13 AM
>Subject: Plugin which can monitor a time build for projects
>
>
>Hello list!
>Could you give me advice how I can monitor a time build for projects? I need get notifications on security group or users of projectswhen build time is very long.
>
>--
>lernen,lernen und lernen
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