OpenSSL is used for sending e-mail notifications when using TLS.
It is available from https://www.openssl.org under the following license:

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 LICENSE ISSUES
  ==============

  The OpenSSL toolkit stays under a dual license, i.e. both the conditions of
  the OpenSSL License and the original SSLeay license apply to the toolkit.
  See below for the actual license texts. Actually both licenses are BSD-style
  Open Source licenses. In case of any license issues related to OpenSSL
  please contact openssl-core@openssl.org.

  OpenSSL License
  ---------------

   ====================================================================
   Copyright (c) 1998-2011 The OpenSSL Project.  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions
  are met:

   1. Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.

   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the
      distribution.

   3. All advertising materials mentioning features or use of this
      software must display the following acknowledgment:
      "This product includes software developed by the OpenSSL Project
      for use in the OpenSSL Toolkit. (http://www.openssl.org/)"

   4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
      endorse or promote products derived from this software without
      prior written permission. For written permission, please contact
      openssl-core@openssl.org.
 
   5. Products derived from this software may not be called "OpenSSL"
      nor may "OpenSSL" appear in their names without prior written
      permission of the OpenSSL Project.
  
   6. Redistributions of any form whatsoever must retain the following
      acknowledgment:
      "This product includes software developed by the OpenSSL Project
      for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 
   THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
   EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
   ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
   OF THE POSSIBILITY OF SUCH DAMAGE.
   ====================================================================
 
   This product includes cryptographic software written by Eric Young
   (eay@cryptsoft.com).  This product includes software written by Tim
   Hudson (tjh@cryptsoft.com).



 Original SSLeay License
 -----------------------

   Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   All rights reserved.

   This package is an SSL implementation written
   by Eric Young (eay@cryptsoft.com).
   The implementation was written so as to conform with Netscapes SSL.

   This library is free for commercial and non-commercial use as long as
   the following conditions are aheared to.  The following conditions
   apply to all code found in this distribution, be it the RC4, RSA,
   lhash, DES, etc., code; not just the SSL code.  The SSL documentation
   included with this distribution is covered by the same copyright terms
   except that the holder is Tim Hudson (tjh@cryptsoft.com).
 
   Copyright remains Eric Young's, and as such any Copyright notices in
   the code are not to be removed.
   If this package is used in a product, Eric Young should be given attribution
   as the author of the parts of the library used.
   This can be in the form of a textual message at program startup or
   in documentation (online or textual) provided with the package.
 
   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met:
   1. Redistributions of source code must retain the copyright
      notice, this list of conditions and the following disclaimer.
   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
   3. All advertising materials mentioning features or use of this software
      must display the following acknowledgement:
      "This product includes cryptographic software written by
       Eric Young (eay@cryptsoft.com)"
      The word 'cryptographic' can be left out if the rouines from the library
      being used are not cryptographic related :-).
   4. If you include any Windows specific code (or a derivative thereof) from
      the apps directory (application code) you must include an acknowledgement:
      "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 
   THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
   ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   SUCH DAMAGE.
  
   The licence and distribution terms for any publically available version or
   derivative of this code cannot be changed.  i.e. this code cannot simply be
   copied and put under another distribution licence
   [including the GNU Public Licence.]
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