diff --git a/psalm.baseline.xml b/psalm.baseline.xml
index 443eb85..6bf7767 100644
--- a/psalm.baseline.xml
+++ b/psalm.baseline.xml
@@ -31,7 +31,7 @@
       <code>$mailId</code>
       <code>$mailId</code>
     </MissingParamType>
-    <MixedArgument occurrences="50">
+    <MixedArgument occurrences="48">
       <code>$mail-&gt;subject</code>
       <code>$mail-&gt;subject</code>
       <code>$mail-&gt;from</code>
@@ -74,8 +74,6 @@
       <code>$partStructure-&gt;id</code>
       <code>$element-&gt;charset</code>
       <code>$element-&gt;text</code>
-      <code>$recipient-&gt;mailbox</code>
-      <code>$recipient-&gt;host</code>
       <code>$recipient-&gt;personal</code>
       <code>$recipient-&gt;personal</code>
       <code>$t[0]-&gt;personal</code>
@@ -102,13 +100,11 @@
       <code>string</code>
       <code>string</code>
     </MixedInferredReturnType>
-    <MixedOperand occurrences="7">
+    <MixedOperand occurrences="5">
       <code>$params[$paramName]</code>
       <code>$subPartNum</code>
       <code>$subPartNum</code>
       <code>$partStructure-&gt;ifid ? $partStructure-&gt;id : ''</code>
-      <code>$recipient-&gt;mailbox</code>
-      <code>$recipient-&gt;host</code>
       <code>$t[0]-&gt;mailbox</code>
     </MixedOperand>
     <MixedPropertyFetch occurrences="20">
diff --git a/src/PhpImap/Mailbox.php b/src/PhpImap/Mailbox.php
index 429ad57..8f980a0 100644
--- a/src/PhpImap/Mailbox.php
+++ b/src/PhpImap/Mailbox.php
@@ -1677,14 +1677,28 @@ protected function getCombinedPath($folder, $absolute = false)
      */
     protected function possiblyGetEmailAndNameFromRecipient(object $recipient)
     {
-        if (isset($recipient->mailbox, $recipient->host) && '' !== trim($recipient->mailbox) && '' !== trim($recipient->host)) {
-            $recipientEmail = strtolower($recipient->mailbox.'@'.$recipient->host);
+        if (isset($recipient->mailbox, $recipient->host)) {
+            /** @var mixed */
+            $recipientMailbox = $recipient->mailbox;
+
+            /** @var mixed */
+            $recipientHost = $recipient->host;
+
+            if (!\is_string($recipientMailbox)) {
+                throw new UnexpectedValueException('mailbox was present on argument 1 passed to '.__METHOD__.'() but was not a string!');
+            } elseif (!\is_string($recipientHost)) {
+                throw new UnexpectedValueException('host was present on argument 1 passed to '.__METHOD__.'() but was not a string!');
+            }
+
+            if ('' !== trim($recipientMailbox) && '' !== trim($recipientHost)) {
+                $recipientEmail = strtolower($recipientMailbox.'@'.$recipientHost);
             $recipientName = (isset($recipient->personal) and !empty(trim($recipient->personal))) ? $this->decodeMimeStr($recipient->personal, $this->getServerEncoding()) : null;
 
             return [
                 $recipientEmail,
                 $recipientName,
             ];
+            }
         }
 
         return null;