There are now two branches of the mail portlet project in the Liferay incubator - one for Liferay 5.2 and one for 5.3 (trunk).
The 5.3 version of the mail portlet does compile correctly against the current Liferay trunk but runs into the issue you mentioned (with basePersistence etc.) because of Spring configuration problems. This problem is not specific to the Vaadin mail portlet but rather affects the common back-end used by the Vaadin and JSP mail portlets.
These problems were caused by the deletion of several classes in the com.liferay.portal.spring.aop package in Liferay trunk, apparently when the issue LPS-5138 was addressed.
As the issue is not limited to the Vaadin mail portlet but concerns some back-end code, I have (re)contacted Liferay on this.
I hope this will be resolved soon.
I have commented out the offending parts of the (JSP) mail portlet Spring configuration, which appear not to be required with Liferay 5.2 and 5.3. At the same time, I re-activated the Vaadin mail portlet and converted it to conform with JSR-286 (Portlet 2.0 specification).
Note that this change requires deploying the theme of the mail portlet directly on the portal, as the JSR-286 Vaadin portlet cannot serve it from the WAR.
The changes are in Liferay SVN (plugins/incubation/portlets/mail-portlet) for Liferay 5.3.
For testing, you can also try the attached pre-built package. To install:
rename the vaadin_mail_portlet_theme.zip.jar file to .zip (renamed as zip files are not allowed on the forum)
unzip the theme ZIP in webapps/ROOT/html/ of your portal
deploy the WAR
Note also that this version is for the moment almost untested (but starts on the latest Liferay 5.3 trunk). The JSP version of the mail portlet is broken in this package (only the main page works) as well as in SVN. 11160.war (905 KB) 11161.jar (26.1 KB)
The mail portlet certainly works quite well… however I haven’t figured out how to get it to save the outgoing emails in the sent folder - am I missing something, or is this a feature that is still to be implemented?