diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..c639d6b
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2021 HackRU
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+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.
diff --git a/deployment/config.prod.py b/deployment/config.prod.py
index b49dedc..f7fe44b 100644
--- a/deployment/config.prod.py
+++ b/deployment/config.prod.py
@@ -47,7 +47,7 @@ class GOOGLE_CAL:
      datetime(int(os.getenv("PRODUCTION_END_YEAR", )), int(os.getenv("PRODUCTION_END_MONTH", )), int(os.getenv("PRODUCTION_END_DAY", )), int(os.getenv("PRODUCTION_END_HOUR", )), tzinfo=TIMEZONE)],
     # reopen during the event of
     [datetime(int(os.getenv("PRODUCTION_DAY_OF_START_YEAR", )), int(os.getenv("PRODUCTION_DAY_OF_START_MONTH", )), int(os.getenv("PRODUCTION_DAY_OF_START_DAY", )), int(os.getenv("PRODUCTION_DAY_OF_START_HOUR", )), tzinfo=TIMEZONE),
-     datetime(int(os.getenv("PRODUCTION_DAY_OF_END_YEAR", )), int(os.getenv("PRODUCTION_DAY_OF_START_MONTH", )), int(os.getenv("PRODUCTION_DAY_OF_END_DAY", )), int(os.getenv("PRODUCTION_DAY_OF_END_HOUR", )), tzinfo=TIMEZONE)]
+     datetime(int(os.getenv("PRODUCTION_DAY_OF_END_YEAR", )), int(os.getenv("PRODUCTION_DAY_OF_END_MONTH", )), int(os.getenv("PRODUCTION_DAY_OF_END_DAY", )), int(os.getenv("PRODUCTION_DAY_OF_END_HOUR", )), tzinfo=TIMEZONE)]
 ]
 
 AWS = {
diff --git a/deployment/deploy_develop.sh b/deployment/deploy_develop.sh
index 7ec8cb3..032aa6d 100644
--- a/deployment/deploy_develop.sh
+++ b/deployment/deploy_develop.sh
@@ -20,7 +20,9 @@ declare -a env_vars=(
  "DEVELOP_SLACK_API_TOKEN"
  "DEVELOP_SLACK_CHANNEL_ID"
  "DEVELOP_RESUME_BUCKET"
- "DEVELOP_WAIVER_BUCKET")
+ "DEVELOP_WAIVER_BUCKET"
+ "DEVELOP_AWS_ACCESS_KEY_ID"
+ "DEVELOP_AWS_SECRET_ACCESS_KEY")
  
 echo "For loop"
 # Disabled environment variables:
diff --git a/deployment/deploy_production.sh b/deployment/deploy_production.sh
index 5d0865a..ee3a70e 100644
--- a/deployment/deploy_production.sh
+++ b/deployment/deploy_production.sh
@@ -35,7 +35,7 @@ declare -a env_vars=(
  "PRODUCTION_DAY_OF_START_DAY"     
  "PRODUCTION_DAY_OF_START_HOUR"
  "PRODUCTION_DAY_OF_END_YEAR"  
- "PRODUCTION_DAY_OF_START_MONTH" 
+ "PRODUCTION_DAY_OF_END_MONTH"
  "PRODUCTION_DAY_OF_END_DAY"  
  "PRODUCTION_DAY_OF_END_HOUR")
  
diff --git a/qr_generator/qr_requirements.txt b/qr_generator/qr_requirements.txt
index 2fd3618..7dfe26d 100644
--- a/qr_generator/qr_requirements.txt
+++ b/qr_generator/qr_requirements.txt
@@ -1,3 +1,3 @@
 qrcode==6.1
-Pillow==6.2.2
+Pillow==7.1.0
 fpdf==1.7.2
\ No newline at end of file
diff --git a/src/cal_announce.py b/src/cal_announce.py
index 3415ca7..ebb1565 100644
--- a/src/cal_announce.py
+++ b/src/cal_announce.py
@@ -42,8 +42,8 @@ def refresh_cache():
         # refresh cache
         token = config.SLACK_KEYS['token']
         channel = config.SLACK_KEYS['channel']
-        url = 'https://slack.com/api/channels.history'
-        params = {'token': token, 'channel': channel, 'count': num_messages}
+        url = 'https://slack.com/api/conversations.history'
+        params = {'token': token, 'channel': channel, 'limit': num_messages}
         result = requests.get(url, params)
         reply = result.json()
         if not reply.get('ok'):
diff --git a/src/slack.py b/src/slack.py
index b316a88..598bbb6 100644
--- a/src/slack.py
+++ b/src/slack.py
@@ -11,12 +11,37 @@ def create_error_response(err_msg: str):
 
 
 def process_slack_error(error_str: str):
-    if error_str in ["user_not_found", "user_not_visible", "user_disabled"]:
+    if error_str == "contains_invalid_user":
         return add_cors_headers(
-                {"statusCode": 403, "body": f"There was an error with the user id's provided: {error_str}"})
+                {"statusCode": 403, "body": f"{error_str}: The id for one of the provided users were invalid"})
+    elif error_str == "user_not_found": 
+        return add_cors_headers(
+                {"statusCode": 403, "body": f"{error_str}: The id for both of the provided users were invalid"})
+    elif error_str == "user_not_visible": 
+        return add_cors_headers(
+                {"statusCode": 403, "body": f"{error_str}: The calling user is restricted from seeing the requested user"})
+    elif error_str == "user_disabled":
+        return add_cors_headers(
+                {"statusCode": 403, "body": f"{error_str}: One or both user accounts are disabled"})
     else:
         return create_error_response(f"Encountered a slack API error: {error_str}")
 
+def get_slack_id(email):
+    # creates the link, payload and headers to make the request for the ID
+    api_link = r"https://slack.com/api/users.lookupByEmail"
+    slack_api_payload = {"token": config.SLACK_KEYS["token"], "email": f"{email}"}
+    slack_api_headers = {"Content-Type": "application/x-www-form-urlencoded"}
+    response = requests.post(url=api_link, data=slack_api_payload, headers=slack_api_headers)
+    if response.status_code != 200:
+        return
+    # fetches the json and examines it to determine if it was successful
+    response_json = response.json()
+    was_successful = response_json["ok"]
+    # in case of failure, error message is attached and returned back
+    if not was_successful:
+        return 
+    # if everything goes well, fetches the necessary id to create the link
+    return response_json["user"]["id"]
 
 @ensure_schema({
     "type": "object",
@@ -36,13 +61,20 @@ def generate_dm_link(event, context, user=None):
     # ensures Slack Token is present in the config
     if "token" not in config.SLACK_KEYS or not config.SLACK_KEYS["token"]:
         return create_error_response("Slack API token not configured")
-    # fetches the slack id from their LCS profile
     this_slack_id = user.get("slack_id", None)
     # fetches the other user's slack id from their LCS profile
     other_slack_id = other_user.get("slack_id", None)
     # ensures both id's exist
-    if this_slack_id is None or other_slack_id is None:
-        return add_cors_headers({"statusCode": 403, "body": "Slack ID not present within LCS for the given user(s)"})
+    if this_slack_id is None:
+        this_slack_id = get_slack_id(user.get("email", None))
+        if this_slack_id is None:
+            return add_cors_headers({"statusCode": 403, "body": "Requester's Slack ID not present within LCS and email is not linked to a Slack ID"})
+    if other_slack_id is None:
+        other_slack_id = get_slack_id(other_user.get("email", None))
+        if other_slack_id is None:
+            return add_cors_headers({"statusCode": 403, "body": "Other user's Slack ID not present within LCS and email is not linked to a Slack ID"})
+    
+    
     # creates the link, payload and headers to make the request
     api_link = r"https://slack.com/api/conversations.open"
     slack_api_payload = {"token": config.SLACK_KEYS["token"], "users": f"{this_slack_id},{other_slack_id}"}
@@ -62,6 +94,6 @@ def generate_dm_link(event, context, user=None):
     creation_info = response_json["channel"]
     dm_id = creation_info["id"]
     server_id = creation_info["shared_team_ids"][0]
-    link_to_dm = f"https://apps.slack.com/client/{server_id}/{dm_id}"
+    link_to_dm = f"https://app.slack.com/client/{server_id}/{dm_id}"
     # returns the link and OK status code
     return add_cors_headers({"statusCode": 200, "body": {"slack_dm_link": link_to_dm}})
diff --git a/tests/test_slack.py b/tests/test_slack.py
index 1c56192..aed5fbc 100644
--- a/tests/test_slack.py
+++ b/tests/test_slack.py
@@ -4,12 +4,14 @@
 
 # credentials of the generator
 email = "generator@test.com"
+email_linked = "email@mailmyrss.com"
 password = "temp_password"
 token = None
 slack_id = "U010WR7TMAQ"
 
 # credentials of the other user
 other_email = "other@test.com"
+other_email_linked = "other_email@mailmyrss.com"
 other_password = "secure_password"
 other_slack_id = "U010WRFRJ7N"
 
@@ -58,6 +60,16 @@ def setup_module(m):
     assert result["statusCode"] == 200
     assert bool(config.SLACK_KEYS["token"])
 
+    # create a dummy user with linked email to slack
+    result = authorize.create_user({"email": email_linked, "password": password}, {})
+    assert result["statusCode"] == 200
+    assert bool(config.SLACK_KEYS["token"])
+
+    # create a dummy user with linked email to slack
+    result = authorize.create_user({"email": other_email_linked, "password": other_password}, {})
+    assert result["statusCode"] == 200
+    assert bool(config.SLACK_KEYS["token"])
+
     # sets the slack id in the db documents
     db = util.coll("users")
     set_slack_id(email, slack_id)
@@ -94,30 +106,48 @@ def test_misconfigured_slack_token():
     config.SLACK_KEYS["token"] = slack_token
 
 
-def test_missing_slack_id():
+def test_missing_slack_id_and_unlinked_email():
     unset_slack_id(email)
     response = generate_dm_link(payload, {})
     assert response["statusCode"] == 403
+    assert response["body"] == "Requester's Slack ID not present within LCS and email is not linked to a Slack ID"
     set_slack_id(email, slack_id)
 
     unset_slack_id(other_email)
     response = generate_dm_link(payload, {})
     assert response["statusCode"] == 403
+    assert response["body"] == "Other user's Slack ID not present within LCS and email is not linked to a Slack ID"
     set_slack_id(other_email, other_slack_id)
 
 
 def test_invalid_slack_id():
     set_slack_id(email, "bad slack id")
     response = generate_dm_link(payload, {})
-    assert response["statusCode"] == 503
+    assert response["statusCode"] == 403
+    assert response["body"] == "contains_invalid_user: The id for one of the provided users were invalid"
     set_slack_id(email, slack_id)
 
     set_slack_id(other_email, "bad slack id")
     response = generate_dm_link(payload, {})
-    assert response["statusCode"] == 503
+    assert response["statusCode"] == 403
+    assert response["body"] == "contains_invalid_user: The id for one of the provided users were invalid"
+    set_slack_id(other_email, other_slack_id)
+
+    set_slack_id(email, "bad slack id")
+    set_slack_id(other_email, "bad slack id")
+    response = generate_dm_link(payload, {})
+    assert response["statusCode"] == 403
+    assert response["body"] == "user_not_found: The id for both of the provided users were invalid"
+    set_slack_id(email, slack_id)
     set_slack_id(other_email, other_slack_id)
 
 
 def test_valid_use():
     response = generate_dm_link(payload, {})
     assert response["statusCode"] == 200
+
+def test_missing_ids_with_linked_emails():
+    payload["other_email"] = other_email_linked
+    response = generate_dm_link(payload, {})
+    assert response["statusCode"] == 200
+