diff --git a/openbis_standard_technologies/dist/core-plugins/eln-lims/1/dss/drop-boxes/eln-lims-dropbox/eln-lims-dropbox.py b/openbis_standard_technologies/dist/core-plugins/eln-lims/1/dss/drop-boxes/eln-lims-dropbox/eln-lims-dropbox.py
index f6bd11ccd8b3f8cbd21db3f5dc1c4d722ca717eb..95f3762335386ab4446357123d92637bf0c111b6 100644
--- a/openbis_standard_technologies/dist/core-plugins/eln-lims/1/dss/drop-boxes/eln-lims-dropbox/eln-lims-dropbox.py
+++ b/openbis_standard_technologies/dist/core-plugins/eln-lims/1/dss/drop-boxes/eln-lims-dropbox/eln-lims-dropbox.py
@@ -196,8 +196,8 @@ def process(transaction):
 
 
 def getContactsEmailAddresses(transaction):
-    emailString = getThreadProperties(transaction)["mail.addresses.dropbox-errors"]
-    return re.split("[,;]", emailString)
+    emailString = getThreadProperties(transaction).get("mail.addresses.dropbox-errors")
+    return re.split("[,;]", emailString) if emailString is not None else []
 
 
 def reportIssue(transaction, errorMessage, emailAddress):