diff --git a/notifiers/providers/email.py b/notifiers/providers/email.py
index dbdbb9fd..ef449828 100644
--- a/notifiers/providers/email.py
+++ b/notifiers/providers/email.py
@@ -1,11 +1,12 @@
 import getpass
+import mimetypes
 import smtplib
 import socket
 from email.message import EmailMessage
-from email.mime.application import MIMEApplication
 from email.utils import formatdate
 from pathlib import Path
 from smtplib import SMTPAuthenticationError, SMTPServerDisconnected, SMTPSenderRefused
+from typing import Tuple, List
 
 from ..core import Provider, Response
 from ..utils.schema.helpers import one_or_more, list_to_commas
@@ -82,6 +83,17 @@ class SMTP(Provider):
         "additionalProperties": False,
     }
 
+    @staticmethod
+    def _get_mimetype(attachment: Path) -> Tuple[str, str]:
+        """Taken from https://docs.python.org/3/library/email.examples.html"""
+        ctype, encoding = mimetypes.guess_type(str(attachment))
+        if ctype is None or encoding is not None:
+            # No guess could be made, or the file is encoded (compressed), so
+            # use a generic bag-of-bits type.
+            ctype = 'application/octet-stream'
+        maintype, subtype = ctype.split('/', 1)
+        return maintype, subtype
+
     def __init__(self):
         super().__init__()
         self.smtp_server = None
@@ -119,14 +131,11 @@ def _build_email(data: dict) -> EmailMessage:
         email.add_alternative(data["message"], subtype=content_type)
         return email
 
-    @staticmethod
-    def _add_attachments(data: dict, email: EmailMessage) -> EmailMessage:
-        for attachment in data["attachments"]:
-            file = Path(attachment).read_bytes()
-            part = MIMEApplication(file)
-            part.add_header("Content-Disposition", "attachment", filename=attachment)
-            email.attach(part)
-        return email
+    def _add_attachments(self, attachments: List[str], email: EmailMessage):
+        for attachment in attachments:
+            attachment = Path(attachment)
+            maintype, subtype = self._get_mimetype(attachment)
+            email.add_attachment(attachment.read_bytes(), maintype=maintype, subtype=subtype, filename=attachment.name)
 
     def _connect_to_server(self, data: dict):
         self.smtp_server = smtplib.SMTP_SSL if data["ssl"] else smtplib.SMTP
@@ -155,7 +164,7 @@ def _send_notification(self, data: dict) -> Response:
                 self._connect_to_server(data)
             email = self._build_email(data)
             if data.get("attachments"):
-                email = self._add_attachments(data, email)
+                self._add_attachments(data['attachments'], email)
             self.smtp_server.send_message(email)
         except (
             SMTPServerDisconnected,
diff --git a/source/changelog.rst b/source/changelog.rst
index d8dd2750..902123e8 100644
--- a/source/changelog.rst
+++ b/source/changelog.rst
@@ -7,6 +7,9 @@ Changelog
 ------------------
 
 - Added ability to cancel login to SMTP/GMAIL if credentials are used (`#210 <https://github.com/notifiers/notifiers/issues/210>`_, `#266 <https://github.com/notifiers/notifiers/pull/266>`_)
+- Loosened dependencies (`#209 <https://github.com/notifiers/notifiers/issues/209>`_, `#266 <https://github.com/notifiers/notifiers/pull/271>`_)
+- Added mimetype guessing for email (`#239 <https://github.com/notifiers/notifiers/issues/239>`_, `#266 <https://github.com/notifiers/notifiers/pull/271>`_)
+
 
 1.0.4
 ------
diff --git a/tests/providers/test_smtp.py b/tests/providers/test_smtp.py
index 4eb12140..595684e6 100644
--- a/tests/providers/test_smtp.py
+++ b/tests/providers/test_smtp.py
@@ -1,3 +1,5 @@
+from email.message import EmailMessage
+
 import pytest
 
 from notifiers.exceptions import BadArguments, NotificationError
@@ -64,6 +66,22 @@ def test_attachment(self, provider, tmpdir):
         )
         assert rsp.data["attachments"] == attachments
 
+    def test_attachment_mimetypes(self, provider, tmpdir):
+        dir_ = tmpdir.mkdir("sub")
+        file_1 = dir_.join("foo.txt")
+        file_1.write("foo")
+        file_2 = dir_.join("bar.jpg")
+        file_2.write("foo")
+        file_3 = dir_.join("baz.pdf")
+        file_3.write("foo")
+        attachments = [str(file_1), str(file_2), str(file_3)]
+        email = EmailMessage()
+        provider._add_attachments(attachments=attachments, email=email)
+        attach1, attach2, attach3 = email.iter_attachments()
+        assert attach1.get_content_type() == 'text/plain'
+        assert attach2.get_content_type() == 'image/jpeg'
+        assert attach3.get_content_type() == 'application/pdf'
+
     @pytest.mark.online
     def test_smtp_sanity(self, provider, test_message):
         """using Gmail SMTP"""