Some users reported not getting mails, I've checked the deamon logs and found:
[2015-09-03 13:55:14] EXCEPTION: (PhutilProxyException) Permanent failure while executing Task ID 526519. {>} (PhabricatorWorkerPermanentFailureException) Unable to load transactions: PHID-XACT-DREV-wdmrkxdekjwktrf. at [<phabricator>/src/applications/transactions/worker/PhabricatorApplicationTransactionPublishWorker.php:105] arcanist(), phabricator(), phutil() #0 <#2> PhabricatorApplicationTransactionPublishWorker::loadTransactions(DifferentialRevision) called at [<phabricator>/src/applications/transactions/worker/PhabricatorApplicationTransactionPublishWorker.php:19] #1 <#2> PhabricatorApplicationTransactionPublishWorker::doWork() called at [<phabricator>/src/infrastructure/daemon/workers/PhabricatorWorker.php:91] #2 <#2> PhabricatorWorker::executeTask() called at [<phabricator>/src/infrastructure/daemon/workers/storage/PhabricatorWorkerActiveTask.php:162] #3 <#2> PhabricatorWorkerActiveTask::executeTask() called at [<phabricator>/src/infrastructure/daemon/workers/PhabricatorTaskmasterDaemon.php:22] #4 PhabricatorTaskmasterDaemon::run() called at [<phutil>/src/daemon/PhutilDaemon.php:183] #5 PhutilDaemon::execute() called at [<phutil>/scripts/daemon/exec/exec_daemon.php:125]
[2015-09-02 12:49:04] EXCEPTION: (PhutilProxyException) Permanent failure while executing Task ID 524864. {>} (PhabricatorWorkerPermanentFailureException) Unable to load transactions: PHID-XACT-TASK-dpptgavo3cftd7d. at [<phabricator>/src/applications/transactions/worker/PhabricatorApplicationTransactionPublishWorker.php:105] arcanist(), phabricator(), phutil() #0 <#2> PhabricatorApplicationTransactionPublishWorker::loadTransactions(ManiphestTask) called at [<phabricator>/src/applications/transactions/worker/PhabricatorApplicationTransactionPublishWorker.php:19] #1 <#2> PhabricatorApplicationTransactionPublishWorker::doWork() called at [<phabricator>/src/infrastructure/daemon/workers/PhabricatorWorker.php:91] #2 <#2> PhabricatorWorker::executeTask() called at [<phabricator>/src/infrastructure/daemon/workers/storage/PhabricatorWorkerActiveTask.php:162] #3 <#2> PhabricatorWorkerActiveTask::executeTask() called at [<phabricator>/src/infrastructure/daemon/workers/PhabricatorTaskmasterDaemon.php:22] #4 PhabricatorTaskmasterDaemon::run() called at [<phutil>/src/daemon/PhutilDaemon.php:183] #5 PhutilDaemon::execute() called at [<phutil>/scripts/daemon/exec/exec_daemon.php:125]