diff --git a/src/exception.cpp b/src/exception.cpp
index bf37de00..3ea6e25a 100644
--- a/src/exception.cpp
+++ b/src/exception.cpp
@@ -428,20 +428,6 @@ exception* unsupported_option::clone() const { return new unsupported_option(*th
 const char* unsupported_option::name() const throw() { return "unsupported_option"; }
 
 
-//
-// no_service_available
-//
-
-no_service_available::~no_service_available() throw() {}
-no_service_available::no_service_available(const string& proto, const exception& other)
-	: net_exception(proto.empty()
-		? "No service available for this protocol."
-		: "No service available for this protocol: '" + proto + "'.", other) {}
-
-exception* no_service_available::clone() const { return new no_service_available(*this); }
-const char* no_service_available::name() const throw() { return "no_service_available"; }
-
-
 //
 // illegal_state
 //
diff --git a/src/net/serviceFactory.cpp b/src/net/serviceFactory.cpp
index a16098ce..98aee646 100644
--- a/src/net/serviceFactory.cpp
+++ b/src/net/serviceFactory.cpp
@@ -101,7 +101,7 @@ shared_ptr <const serviceFactory::registeredService> serviceFactory::getServiceB
 			return (*it);
 	}
 
-	throw exceptions::no_service_available(name);
+	return null;
 }
 
 
diff --git a/src/net/session.cpp b/src/net/session.cpp
index fcc5dd12..36b9f2c3 100644
--- a/src/net/session.cpp
+++ b/src/net/session.cpp
@@ -74,8 +74,8 @@ shared_ptr <transport> session::getTransport
 	shared_ptr <session> sess(dynamicCast <session>(shared_from_this()));
 	shared_ptr <service> sv = serviceFactory::getInstance()->create(sess, protocol, auth);
 
-	if (sv->getType() != service::TYPE_TRANSPORT)
-		throw exceptions::no_service_available();
+	if (!sv || sv->getType() != service::TYPE_TRANSPORT)
+		return null;
 
 	return dynamicCast <transport>(sv);
 }
@@ -87,8 +87,8 @@ shared_ptr <transport> session::getTransport
 	shared_ptr <session> sess(dynamicCast <session>(shared_from_this()));
 	shared_ptr <service> sv = serviceFactory::getInstance()->create(sess, url, auth);
 
-	if (sv->getType() != service::TYPE_TRANSPORT)
-		throw exceptions::no_service_available();
+	if (!sv || sv->getType() != service::TYPE_TRANSPORT)
+		return null;
 
 	return dynamicCast <transport>(sv);
 }
@@ -106,8 +106,8 @@ shared_ptr <store> session::getStore
 	shared_ptr <session> sess(dynamicCast <session>(shared_from_this()));
 	shared_ptr <service> sv = serviceFactory::getInstance()->create(sess, protocol, auth);
 
-	if (sv->getType() != service::TYPE_STORE)
-		throw exceptions::no_service_available();
+	if (!sv || sv->getType() != service::TYPE_STORE)
+		return null;
 
 	return dynamicCast <store>(sv);
 }
@@ -119,8 +119,8 @@ shared_ptr <store> session::getStore
 	shared_ptr <session> sess(dynamicCast <session>(shared_from_this()));
 	shared_ptr <service> sv = serviceFactory::getInstance()->create(sess, url, auth);
 
-	if (sv->getType() != service::TYPE_STORE)
-		throw exceptions::no_service_available();
+	if (!sv || sv->getType() != service::TYPE_STORE)
+		return null;
 
 	return dynamicCast <store>(sv);
 }
diff --git a/vmime/exception.hpp b/vmime/exception.hpp
index d39ac2a2..f1a5e1a3 100644
--- a/vmime/exception.hpp
+++ b/vmime/exception.hpp
@@ -492,21 +492,6 @@ public:
 };
 
 
-/** No service available for this protocol.
-  */
-
-class VMIME_EXPORT no_service_available : public net_exception
-{
-public:
-
-	no_service_available(const string& proto = "", const exception& other = NO_EXCEPTION);
-	~no_service_available() throw();
-
-	exception* clone() const;
-	const char* name() const throw();
-};
-
-
 /** The current state of the object does not permit to execute the
   * operation (for example, you try to close a folder which is not open).
   */
diff --git a/vmime/net/serviceFactory.hpp b/vmime/net/serviceFactory.hpp
index baf692a8..9295b345 100644
--- a/vmime/net/serviceFactory.hpp
+++ b/vmime/net/serviceFactory.hpp
@@ -101,9 +101,8 @@ public:
 	  * @param sess session
 	  * @param protocol protocol name (eg. "pop3")
 	  * @param auth authenticator used to provide credentials (can be NULL if not used)
-	  * @return a new service instance for the specified protocol
-	  * @throw exceptions::no_service_available if no service is registered
-	  * for this protocol
+	  * @return a new service instance for the specified protocol, or NULL if no service
+	  * is registered for this protocol
 	  */
 	shared_ptr <service> create
 		(shared_ptr <session> sess,
@@ -116,9 +115,8 @@ public:
 	  * @param u full URL with at least protocol and server (you can also specify
 	  * port, username and password)
 	  * @param auth authenticator used to provide credentials (can be NULL if not used)
-	  * @return a new service instance for the specified protocol
-	  * @throw exceptions::no_service_available if no service is registered
-	  * for this protocol
+	  * @return a new service instance for the specified protocol or NULL if no service
+	  * is registered for this protocol
 	  */
 	shared_ptr <service> create
 		(shared_ptr <session> sess,
@@ -128,8 +126,7 @@ public:
 	/** Return information about a registered protocol.
 	  *
 	  * @param protocol protocol name
-	  * @return information about this protocol
-	  * @throw exceptions::no_service_available if no service is registered
+	  * @return information about this protocol, or NULL if no service is registered
 	  * for this protocol
 	  */
 	shared_ptr <const registeredService> getServiceByProtocol(const string& protocol) const;
diff --git a/vmime/net/session.hpp b/vmime/net/session.hpp
index 59337879..a7e0ea1a 100644
--- a/vmime/net/session.hpp
+++ b/vmime/net/session.hpp
@@ -70,7 +70,8 @@ public:
 	  * @param auth authenticator object to use for the new transport service. If
 	  * NULL, a default one is used. The default authenticator simply return user
 	  * credentials by reading the session properties "auth.username" and "auth.password".
-	  * @return a new transport service
+	  * @return a new transport service, or NULL if no service is registered for this
+	  * protocol or is not a transport protocol
 	  */
 	shared_ptr <transport> getTransport
 		(shared_ptr <security::authenticator> auth = null);
@@ -81,7 +82,8 @@ public:
 	  * @param auth authenticator object to use for the new transport service. If
 	  * NULL, a default one is used. The default authenticator simply return user
 	  * credentials by reading the session properties "auth.username" and "auth.password".
-	  * @return a new transport service
+	  * @return a new transport service, or NULL if no service is registered for this
+	  * protocol or is not a transport protocol
 	  */
 	shared_ptr <transport> getTransport
 		(const string& protocol,
@@ -93,7 +95,8 @@ public:
 	  * @param auth authenticator object to use for the new transport service. If
 	  * NULL, a default one is used. The default authenticator simply return user
 	  * credentials by reading the session properties "auth.username" and "auth.password".
-	  * @return a new transport service
+	  * @return a new transport service, or NULL if no service is registered for this
+	  * protocol or is not a transport protocol
 	  */
 	shared_ptr <transport> getTransport
 		(const utility::url& url,
@@ -107,7 +110,8 @@ public:
 	  * @param auth authenticator object to use for the new store service. If
 	  * NULL, a default one is used. The default authenticator simply return user
 	  * credentials by reading the session properties "auth.username" and "auth.password".
-	  * @return a new store service
+	  * @return a new store service, or NULL if no service is registered for this
+	  * protocol or is not a store protocol
 	  */
 	shared_ptr <store> getStore(shared_ptr <security::authenticator> auth = null);
 
@@ -117,7 +121,8 @@ public:
 	  * @param auth authenticator object to use for the new store service. If
 	  * NULL, a default one is used. The default authenticator simply return user
 	  * credentials by reading the session properties "auth.username" and "auth.password".
-	  * @return a new store service
+	  * @return a new store service, or NULL if no service is registered for this
+	  * protocol or is not a store protocol
 	  */
 	shared_ptr <store> getStore
 		(const string& protocol,
@@ -129,7 +134,8 @@ public:
 	  * @param auth authenticator object to use for the new store service. If
 	  * NULL, a default one is used. The default authenticator simply return user
 	  * credentials by reading the session properties "auth.username" and "auth.password".
-	  * @return a new store service
+	  * @return a new store service, or NULL if no service is registered for this
+	  * protocol or is not a store protocol
 	  */
 	shared_ptr <store> getStore
 		(const utility::url& url,