You are using an Email Service Task Type. The Process Instance goes into a HALTED state once the task is encountered and you get the following exception in the BPM log file.

11 Sep 2017 07:46:09,276 [PVM:DB Process Worker-4] [ERROR] com.tibco.bx.core.BxSystemImpl - [ERROR] - {BX_TASK_REPORTED_ERROR} - BX-800009: Task reported an error �{extendedMessage=`Illegal address`, componentClassName=`com.tibco.bx.core.BxSystemImpl`, requestReceived=`null`, hostAddress=`172.31.92.11`, nodeName=`BPMNode`, eventType=`MESSAGE`, messageCategory=`PROCESS_INSTANCE`, componentId=`BX`, managedObjectName=`remittanceet`, stackTrace=`com.tibco.bx.core.faults.BxException: Illegal address
    at com.tibco.bx.core.behaviors.activity.BxExtensionBehavior.doEval(BxExtensionBehavior.java:191)
    at com.tibco.bx.core.behaviors.activity.BxActivityBaseBehavior.eval(BxActivityBaseBehavior.java:884)
    at com.tibco.bx.core.behaviors.activity.BxActivityBaseBehavior.eval(BxActivityBaseBehavior.java:1)
    at com.tibco.pvm.infra.api.impl.util.director.IpmEventDirectorBase.handleModelEvent(IpmEventDirectorBase.java:231)
    at com.tibco.pvm.infra.api.impl.util.director.IpmEventDirectorBase.handleEvent(IpmEventDirectorBase.java:112)
    at com.tibco.pvm.infra.support.work.impl.WorkItemAbstract.execute(WorkItemAbstract.java:189)
    at com.tibco.pvm.db.persist.services.engine.IdbSTWorkRunnable.doWorkBlock(IdbSTWorkRunnable.java:131)
    at com.tibco.pvm.infra.services.engine.impl.STWorkRunnable.run(STWorkRunnable.java:50)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: javax.mail.internet.AddressException: Illegal address in string ``''
    at javax.mail.internet.InternetAddress.<init>(InternetAddress.java:94)
    at com.tibco.bx.extension.email.core.MailPluginImplementation.createEmailAddress(MailPluginImplementation.java:593)
    at com.tibco.bx.extension.email.core.MailPluginImplementation.compileEmailAddresses(MailPluginImplementation.java:539)
    at com.tibco.bx.extension.email.core.MailPluginImplementation.send(MailPluginImplementation.java:284)
    at com.tibco.bx.extension.email.core.EmailTaskActivity.doWork(EmailTaskActivity.java:106)
    at com.tibco.bx.extension.email.core.EmailTaskActivity.eval(EmailTaskActivity.java:75)
    at com.tibco.bx.core.behaviors.activity.BxExtensionBehavior.doEval(BxExtensionBehavior.java:162)
    ... 10 more
`, serviceName=`null`, principalId=`tibco-admin`, priority=`MEDIUM`, managedObjectId=`pvm:0a1231lf`, hostName=`t1ratbp501.ssc.tsc`, creationTime=`2017-09-11T12:46:09.276Z`, applicationActivityInstanceId=`pvm:001i311uv`, correlationId=``, principalName=`tibco-admin`, threadId=`1588`, parentContextId=`null`, moduleName=`/tcs.vmd.expensevendort.bpm/Process Packages/remittanceet.xpdl`, compositeApplicationName=`amx.bpm.app`, applicationActivityName=`SendEmail`, severity=`ERROR`, message=`BX-800009: Task reported an error`, contextId=`null`, threadName=`PVM:DB Process Worker-4`, environmentName=`BPMEnvironment`, messageId=`BX_TASK_REPORTED_ERROR`, �}
11 Sep 2017 07:46:09,276 [PVM:DB Process Worker-4] [ERROR] com.tibco.bx.core.BxSystemImpl - [ERROR] - {BX_TASK_REPORTED_ERROR} - BX-800009: Task reported an error �{extendedMessage=`Illegal address`, componentClassName=`com.tibco.bx.core.BxSystemImpl`, requestReceived=`null`, hostAddress=`172.31.92.11`, nodeName=`BPMNode`, eventType=`MESSAGE`, messageCategory=`PROCESS_INSTANCE`, componentId=`BX`, managedObjectName=`remittanceet`, stackTrace=`com.tibco.bx.core.faults.BxException: Illegal address
    at com.tibco.bx.core.behaviors.activity.BxExtensionBehavior.doEval(BxExtensionBehavior.java:191)
    at com.tibco.bx.core.behaviors.activity.BxActivityBaseBehavior.eval(BxActivityBaseBehavior.java:884)
    at com.tibco.bx.core.behaviors.activity.BxActivityBaseBehavior.eval(BxActivityBaseBehavior.java:1)
    at com.tibco.pvm.infra.api.impl.util.director.IpmEventDirectorBase.handleModelEvent(IpmEventDirectorBase.java:231)
    at com.tibco.pvm.infra.api.impl.util.director.IpmEventDirectorBase.handleEvent(IpmEventDirectorBase.java:112)
    at com.tibco.pvm.infra.support.work.impl.WorkItemAbstract.execute(WorkItemAbstract.java:189)
    at com.tibco.pvm.db.persist.services.engine.IdbSTWorkRunnable.doWorkBlock(IdbSTWorkRunnable.java:131)
    at com.tibco.pvm.infra.services.engine.impl.STWorkRunnable.run(STWorkRunnable.java:50)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: javax.mail.internet.AddressException: Illegal address in string ``''
    at javax.mail.internet.InternetAddress.<init>(InternetAddress.java:94)
    at com.tibco.bx.extension.email.core.MailPluginImplementation.createEmailAddress(MailPluginImplementation.java:593)
    at com.tibco.bx.extension.email.core.MailPluginImplementation.compileEmailAddresses(MailPluginImplementation.java:539)
    at com.tibco.bx.extension.email.core.MailPluginImplementation.send(MailPluginImplementation.java:284)
    at com.tibco.bx.extension.email.core.EmailTaskActivity.doWork(EmailTaskActivity.java:106)
    at com.tibco.bx.extension.email.core.EmailTaskActivity.eval(EmailTaskActivity.java:75)
    at com.tibco.bx.core.behaviors.activity.BxExtensionBehavior.doEval(BxExtensionBehavior.java:162)
    ... 10 more
`, serviceName=`null`, principalId=`tibco-admin`, priority=`MEDIUM`, managedObjectId=`pvm:0a1231lf`, hostName=`t1ratbp501.ssc.tsc`, creationTime=`2017-09-11T12:46:09.276Z`, applicationActivityInstanceId=`pvm:001i311uv`, correlationId=``, principalName=`tibco-admin`, threadId=`1588`, parentContextId=`null`, moduleName=`/tcs.vmd.expensevendort.bpm/Process Packages/remittanceet.xpdl`, compositeApplicationName=`amx.bpm.app`, applicationActivityName=`SendEmail`, severity=`ERROR`, message=`BX-800009: Task reported an error`, contextId=`null`, threadName=`PVM:DB Process Worker-4`, environmentName=`BPMEnvironment`, messageId=`BX_TASK_REPORTED_ERROR`, �}

When using an Email Service Task Type, you get an "Illegal address in string ``''" exception in the BPM.log file.

All Platforms

All fields must be configured correctly. There must be a valid email address in the appropriate field.
 

https://docs.tibco.com/pub/business-studio-bpm-edition/4.2.0/doc/html/GUID-93BA0209-4414-4753-99ED-852122B6A0AB.html