diff --git a/src/services/email_service.py b/src/services/email_service.py
index 59fea2a..bf652e3 100644
--- a/src/services/email_service.py
+++ b/src/services/email_service.py
@@ -22,9 +22,12 @@ from models.common import OperationResult
 from config import Settings
 
 
-def decode_mime_header(header: Optional[str]) -> str:
+def decode_mime_header(header) -> str:
     if not header:
         return ""
+    # Handle bytes input from IMAP
+    if isinstance(header, bytes):
+        header = header.decode("utf-8", errors="replace")
     decoded_parts = []
     for part, encoding in decode_header(header):
         if isinstance(part, bytes):
@@ -516,7 +519,14 @@ class EmailService:
         body_text, body_html = self._get_body(msg)
         text = body_text or ""
 
+        # Ensure text is a string
+        if isinstance(text, bytes):
+            text = text.decode("utf-8", errors="replace")
+
         if not text and body_html:
+            # Ensure body_html is a string before regex
+            if isinstance(body_html, bytes):
+                body_html = body_html.decode("utf-8", errors="replace")
             # Strip HTML tags for snippet
             text = re.sub(r"<[^>]+>", "", body_html)
             text = re.sub(r"\s+", " ", text).strip()