diff --git a/src/com/fsck/k9/mail/transport/SmtpTransport.java b/src/com/fsck/k9/mail/transport/SmtpTransport.java
index 377be1114..d73f7d910 100644
--- a/src/com/fsck/k9/mail/transport/SmtpTransport.java
+++ b/src/com/fsck/k9/mail/transport/SmtpTransport.java
@@ -182,26 +182,28 @@ public class SmtpTransport extends Transport
             String localHost = localAddress.getHostName();
             String ipAddr = localAddress.getHostAddress();
 
-            if (localHost.equals(ipAddr) || localHost.contains("_"))
+            if (localHost.equals("") || localHost.equals(ipAddr) || localHost.contains("_"))
             {
                 // We don't have a FQDN or the hostname contains invalid
                 // characters (see issue 2143), so use IP address.
-                if (localAddress instanceof Inet6Address)
+                if (!ipAddr.equals(""))
                 {
-                    localHost = "[IPV6:" + ipAddr + "]";
+                    if (localAddress instanceof Inet6Address)
+                    {
+                        localHost = "[IPV6:" + ipAddr + "]";
+                    }
+                    else
+                    {
+                        localHost = "[" + ipAddr + "]";
+                    }
                 }
                 else
                 {
-                    localHost = "[" + ipAddr + "]";
+                    // If the IP address is no good, set a sane default (see issue 2750).
+                    localHost = "android";
                 }
             }
 
-            // If we don't have a hostname for whatever reason, set a sane default (see issue 2750).
-            if (localHost.equals(""))
-            {
-                localHost = "android";
-            }
-
             List<String> results = executeSimpleCommand("EHLO " + localHost);
 
             m8bitEncodingAllowed = results.contains("8BITMIME");