Patch by Zarafa <http://www.zarafa.com/> - small partial backport of some socket handling code from 0.8.1.
Only receiving data is handled better. The patch also adds a timeout, when receiving data from a socket
hasn't worked for 5 minutes. This isn't present in 0.8.1.

--- libvmime-0.7.1/src/platforms/posix/posixSocket.cpp			2007-10-18 11:19:47.000000000 +0200
+++ libvmime-0.7.1/src/platforms/posix/posixSocket.cpp.socket-timeout	2007-10-18 11:02:54.000000000 +0200
@@ -26,6 +26,7 @@
 #include <netinet/in.h>
 #include <netdb.h>
 #include <fcntl.h>
+#include <errno.h>
 
 #include "vmime/exception.hpp"
 
@@ -43,7 +44,7 @@
 //
 
 posixSocket::posixSocket()
-	: m_desc(-1)
+	: m_desc(-1), m_timeouts(0)
 {
 }
 
@@ -101,6 +102,8 @@
 		// Error
 		throw vmime::exceptions::connection_error("Error while connecting socket.");
 	}
+
+	m_timeouts = 0;
 }
 
 
@@ -121,38 +124,62 @@
 	}
 }
 
-
 void posixSocket::receive(vmime::string& buffer)
 {
-	::ssize_t ret = ::recv(m_desc, m_buffer, sizeof(m_buffer), 0);
-
-	if (ret == -1)
-	{
-		// Error or no data
-		return;
-	}
-	else if (ret > 0)
-	{
-		buffer = vmime::string(m_buffer, ret);
-	}
+	const int size = receiveRaw(m_buffer, sizeof(m_buffer));
+	buffer = vmime::string(m_buffer, size);
 }
 
 
 const int posixSocket::receiveRaw(char* buffer, const int count)
 {
-	::ssize_t ret = ::recv(m_desc, buffer, count, 0);
+	fd_set fds;
+	struct timeval tv;
+	int ret;
+
+	FD_ZERO(&fds);
+	FD_SET(m_desc, &fds);
+
+	tv.tv_sec = 10;
+	tv.tv_usec = 0;
+
+	ret = ::select(m_desc+1, &fds, NULL, NULL, &tv);
+	if (ret < 0)
+	{
+		if (errno != EAGAIN)
+			throwSocketError(errno);
+
+		m_timeouts++;
+		if (m_timeouts > (5*60))
+			throwSocketError(errno); // SMTP server did not react within 5 minutes
+
+		// No data available at this time
+		return 0;
+	}
 
-	if (ret == -1)
+	ret = ::recv(m_desc, buffer, count, 0);
+
+	if (ret < 0)
 	{
-		// Error or no data
-		return (0);
+		if (errno != EAGAIN)
+			throwSocketError(errno);
+
+		m_timeouts++;
+		if (m_timeouts > (5*60))
+			throwSocketError(errno); // SMTP server did not react within 5 minutes
+
+		// No data available at this time
+		return 0;
 	}
-	else
+	else if (ret == 0)
 	{
-		return (ret);
+		// Host shutdown
+		throwSocketError(ENOTCONN);
 	}
-}
 
+	m_timeouts = 0;
+	return ret;
+}
 
 void posixSocket::send(const vmime::string& buffer)
 {
@@ -166,6 +193,41 @@
 }
 
 
+void posixSocket::throwSocketError(const int err)
+{
+	string msg;
+
+	switch (err)
+	{
+	case EACCES:          msg = "EACCES: permission denied"; break;
+	case EAFNOSUPPORT:    msg = "EAFNOSUPPORT: address family not supported"; break;
+	case EMFILE:          msg = "EMFILE: process file table overflow"; break;
+	case ENFILE:          msg = "ENFILE: system limit reached"; break;
+	case EPROTONOSUPPORT: msg = "EPROTONOSUPPORT: protocol not supported"; break;
+	case EAGAIN:          msg = "EAGAIN: blocking operation"; break;
+	case EBADF:           msg = "EBADF: invalid descriptor"; break;
+	case ECONNRESET:      msg = "ECONNRESET: connection reset by peer"; break;
+	case EFAULT:          msg = "EFAULT: bad user space address"; break;
+	case EINTR:           msg = "EINTR: signal occured before transmission"; break;
+	case EINVAL:          msg = "EINVAL: invalid argument"; break;
+	case EMSGSIZE:        msg = "EMSGSIZE: message cannot be sent atomically"; break;
+	case ENOBUFS:         msg = "ENOBUFS: output queue is full"; break;
+	case ENOMEM:          msg = "ENOMEM: out of memory"; break;
+	case EPIPE:
+	case ENOTCONN:        msg = "ENOTCONN: not connected"; break;
+	case ECONNREFUSED:    msg = "ECONNREFUSED: connection refused"; break;
+	default:
+
+		std::ostringstream oss;
+		oss << ::strerror(err);
+
+		msg = oss.str();
+		break;
+	}
+
+	throw vmime::exceptions::connection_error(msg);
+}
+
 
 
 //
--- libvmime-0.7.1/vmime/platforms/posix/posixSocket.hpp		2007-10-18 11:19:47.000000000 +0200
+++ libvmime-0.7.1/vmime/platforms/posix/posixSocket.hpp.socket-timeout	2007-10-18 10:34:46.000000000 +0200
@@ -49,10 +49,13 @@
 	void send(const vmime::string& buffer);
 	void sendRaw(const char* buffer, const int count);
 
+	void throwSocketError(const int err);
+
 private:
 
 	char m_buffer[65536];
 	int m_desc;
+	int m_timeouts;
 };