Add support for email notifications

NOTICE.txt

@@ -100,6 +100,7 @@ SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 
 https://golangcode.com/get-the-request-ip-addr/
+https://golangcode.com/validate-an-email-address/
 https://github.com/eddturtle/golangcode-site/blob/master/LICENSE
 
 MIT License
@@ -177,3 +178,22 @@ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
+
+
+
+
+https://github.com/Showmax/go-fqdn/blob/master/LICENSE
+
+Copyright since 2015 Showmax s.r.o.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

README.md

@@ -107,7 +107,9 @@ See also:
   - levels, format and output (see [configuration settings
     doc](docs/configure.md))
 
-- Microsoft Teams notifications
+- Optional notifications
+  - Microsoft Teams
+  - Email
   - generated for multiple events
     - alert received
     - disabled user
@@ -153,7 +155,6 @@ Known issues:
 
 - Documentation
   - The docs are beginning to take overall shape, but still need a lot of work
-- Email notifications are not currently supported (see GH-3)
 - Payloads are accepted from any IP Address
   - the expectation is that host-level firewall rules will be used to protect
     against this until a feature can be added to filter access (see GH-18)