diff --git a/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/mail/MailReader.kt b/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/mail/MailReader.kt
index 20377ec..192b2f5 100644
--- a/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/mail/MailReader.kt
+++ b/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/mail/MailReader.kt
@@ -103,7 +103,7 @@ class MailReader(
                 if (attachmentsWithEInvoice.isNotEmpty()) {
                     return@mapNotNull MailWithInvoice(
                         message.from.joinToString(), message.subject,
-                        map(message.sentDate), map(message.receivedDate), message.messageNumber,
+                        message.sentDate?.let { map(it) }, map(message.receivedDate), message.messageNumber,
                         attachmentsWithEInvoice
                     )
                 }
diff --git a/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/mail/MailWithInvoice.kt b/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/mail/MailWithInvoice.kt
index 92ad0a1..7052649 100644
--- a/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/mail/MailWithInvoice.kt
+++ b/e-invoicing-domain/src/main/kotlin/net/codinux/invoicing/mail/MailWithInvoice.kt
@@ -6,10 +6,10 @@ import java.time.ZoneId
 class MailWithInvoice(
     val sender: String,
     val subject: String,
-    val sent: Instant,
+    val sent: Instant?,
     val received: Instant,
     val messageNumber: Int,
     val attachmentsWithEInvoice: List<MailAttachmentWithEInvoice>
 ) {
-    override fun toString() = "${sent.atZone(ZoneId.systemDefault()).toLocalDate()} $sender: $subject, ${attachmentsWithEInvoice.size} invoice(s)"
+    override fun toString() = "${(sent ?: received).atZone(ZoneId.systemDefault()).toLocalDate()} $sender: $subject, ${attachmentsWithEInvoice.size} invoice(s)"
 }
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