diff --git a/micromail.py b/micromail.py
index 17cec66..84ac399 100644
--- a/micromail.py
+++ b/micromail.py
@@ -6,9 +6,8 @@ from datetime import datetime, timedelta, timezone
 
 
 class MicromailClient:
-    def __init__(self, host, port, ssl=False, starttls=False):
+    def __init__(self, host, port=0, ssl=False, starttls=False):
         self.host = host
-        self.port = port
 
         if ssl and starttls:
             raise Error("Cannot use both SSL and STARTTLS at the same time.")
@@ -16,6 +15,15 @@ class MicromailClient:
         self.ssl = ssl
         self.starttls = starttls
 
+        if port == 0:
+            if ssl:
+                port = 465
+            elif starttls:
+                port = 587
+            else:
+                port = 25
+        self.port = port
+
         self.socket = None
         self.username = None