diff --git a/docker/backend/shard.lock b/docker/backend/shard.lock
index 1a0e96b..dc8b1fd 100644
--- a/docker/backend/shard.lock
+++ b/docker/backend/shard.lock
@@ -62,7 +62,7 @@ shards:
 
   mosquito:
     git: https://github.com/mosquito-cr/mosquito.git
-    version: 0.11.2
+    version: 1.0.0.rc1+git.commit.afd53dd241447b60ece9232b6c71669b192baaa4
 
   openssl_ext:
     git: https://github.com/spider-gazelle/openssl_ext.git
diff --git a/docker/backend/shard.yml b/docker/backend/shard.yml
index ddc93b4..d167d61 100644
--- a/docker/backend/shard.yml
+++ b/docker/backend/shard.yml
@@ -46,6 +46,7 @@ dependencies:
     github: juanedi/micrate
   mosquito:
     github: mosquito-cr/mosquito
+    branch: master
   quartz_mailer:
     github: amberframework/quartz-mailer
   kilt:
diff --git a/docker/backend/src/backend/api/schema/helpers.cr b/docker/backend/src/backend/api/schema/helpers.cr
index c611bdf..513473d 100644
--- a/docker/backend/src/backend/api/schema/helpers.cr
+++ b/docker/backend/src/backend/api/schema/helpers.cr
@@ -19,39 +19,33 @@ module Backend
     module Schema
       # Schema helper macros
       module Helpers
-        # Object helpers
-        module ObjectMacros
-          # Defines field property and GraphQL specific getter
-          macro field(type)
-            property {{ type.var }} {% if type.value %} = {{ type.value }}{% end %}
+        # Defines field property and GraphQL specific getter
+        macro field(type)
+          property {{ type.var }} {% if type.value %} = {{ type.value }}{% end %}
 
-            @[GraphQL::Field]
-            def {{ type.var }} : {{ type.type }}
-              @{{ type.var }}
-            end
+          @[GraphQL::Field]
+          def {{ type.var }} : {{ type.type }}
+            @{{ type.var }}
           end
         end
 
-        # DB model field helpers
-        module DbObject
-          # Defines DB model field helper functions
-          macro db_object(type)
-            private property model
+        # Defines DB model field helper functions
+        macro db_object(type)
+          private property model
 
-            def initialize(@model : {{ type }})
-            end
+          def initialize(@model : {{ type }})
+          end
 
-            def initialize(id : Int32)
-              @model = {{ type }}.find!(id)
-            end
+          def initialize(id : Int32)
+            @model = {{ type }}.find!(id)
+          end
 
-            {% space_name = type.names.last.underscore.gsub(/_/, " ").capitalize %}
+          {% space_name = type.names.last.underscore.gsub(/_/, " ").capitalize %}
 
-            @[GraphQL::Field]
-            # {{ space_name }}'s ID
-            def id : Int32
-              @model.id.not_nil!.to_i
-            end
+          @[GraphQL::Field]
+          # {{ space_name }}'s ID
+          def id : Int32
+            @model.id.not_nil!.to_i
           end
         end
       end
diff --git a/docker/backend/src/backend/api/schema/mutation.cr b/docker/backend/src/backend/api/schema/mutation.cr
index fcd75a5..6fce16d 100644
--- a/docker/backend/src/backend/api/schema/mutation.cr
+++ b/docker/backend/src/backend/api/schema/mutation.cr
@@ -44,16 +44,12 @@ module Backend
           context.admin!
 
           raise "LDAP user does not exist" if check_ldap && begin
-                                                !Ldap.user(Ldap::Constructor.uid(input.username))
+                                                !Ldap::User.from_username(input.username)
                                               rescue LDAP::Client::AuthError
                                                 true
                                               end
           user = Db::User.create!(username: input.username, role: input.role.to_s, admin: input.admin)
-          Redis::CLIENT.set(
-            "ldap:user:#{user.id.not_nil!}",
-            Ldap.user(Ldap::Constructor.uid(user.username)).to_json,
-            (Backend.config.ldap.cache_refresh_interval * 2).minutes.to_i
-          )
+          Worker::Jobs::CacheLdapUserJob.new(user.id.not_nil!.to_i).enqueue
 
           User.new(user)
         end
diff --git a/docker/backend/src/backend/api/schema/student.cr b/docker/backend/src/backend/api/schema/student.cr
index bfce6eb..5dad9a7 100644
--- a/docker/backend/src/backend/api/schema/student.cr
+++ b/docker/backend/src/backend/api/schema/student.cr
@@ -20,7 +20,7 @@ module Backend
       @[GraphQL::Object]
       # Student model
       class Student < GraphQL::BaseObject
-        include Helpers::DbObject
+        include Helpers
 
         db_object Db::Student
 
diff --git a/docker/backend/src/backend/api/schema/teacher.cr b/docker/backend/src/backend/api/schema/teacher.cr
index 6368a5f..7b15bab 100644
--- a/docker/backend/src/backend/api/schema/teacher.cr
+++ b/docker/backend/src/backend/api/schema/teacher.cr
@@ -20,7 +20,7 @@ module Backend
       @[GraphQL::Object]
       # Teacher model
       class Teacher < GraphQL::BaseObject
-        include Helpers::DbObject
+        include Helpers
 
         db_object Db::Teacher
 
diff --git a/docker/backend/src/backend/api/schema/teacher_vote.cr b/docker/backend/src/backend/api/schema/teacher_vote.cr
index 2d29b4d..d075de0 100644
--- a/docker/backend/src/backend/api/schema/teacher_vote.cr
+++ b/docker/backend/src/backend/api/schema/teacher_vote.cr
@@ -20,7 +20,7 @@ module Backend
       @[GraphQL::Object]
       # Teacher vote model
       class TeacherVote < GraphQL::BaseObject
-        include Helpers::DbObject
+        include Helpers
 
         db_object Db::TeacherVote
 
diff --git a/docker/backend/src/backend/api/schema/user.cr b/docker/backend/src/backend/api/schema/user.cr
index 257d257..3bbac50 100644
--- a/docker/backend/src/backend/api/schema/user.cr
+++ b/docker/backend/src/backend/api/schema/user.cr
@@ -20,26 +20,34 @@ module Backend
       @[GraphQL::Object]
       # User model
       class User < GraphQL::BaseObject
-        include Helpers::DbObject
+        include Helpers
 
         db_object Db::User
 
+        # LDAP user data
+        getter ldap : Ldap::User?
+
+        # Refreshes LDAP user data
+        def refresh_ldap : Ldap::User
+          (@ldap ||= Ldap::User.from_json(Redis::CLIENT.get("ldap:user:#{id}").as(String))).not_nil!
+        end
+
         @[GraphQL::Field]
         # User's first name
         def first_name : String
-          @model.first_name
+          refresh_ldap.first_name
         end
 
         @[GraphQL::Field]
         # User's last name
         def last_name : String
-          @model.last_name
+          refresh_ldap.last_name
         end
 
         @[GraphQL::Field]
         # User's full name
         def name : String
-          @model.name
+          refresh_ldap.name
         end
 
         @[GraphQL::Field]
@@ -51,7 +59,7 @@ module Backend
         @[GraphQL::Field]
         # User's email
         def email : String
-          @model.email
+          refresh_ldap.email
         end
 
         @[GraphQL::Field]
diff --git a/docker/backend/src/backend/api/schema/vote.cr b/docker/backend/src/backend/api/schema/vote.cr
index af627e9..83e349e 100644
--- a/docker/backend/src/backend/api/schema/vote.cr
+++ b/docker/backend/src/backend/api/schema/vote.cr
@@ -20,7 +20,7 @@ module Backend
       @[GraphQL::Object]
       # Vote model
       class Vote < GraphQL::BaseObject
-        include Helpers::DbObject
+        include Helpers
 
         db_object Db::Vote
 
diff --git a/docker/backend/src/backend/db/user.cr b/docker/backend/src/backend/db/user.cr
index 0df968a..5e37bbf 100644
--- a/docker/backend/src/backend/db/user.cr
+++ b/docker/backend/src/backend/db/user.cr
@@ -20,9 +20,6 @@ module Backend
     class User < Granite::Base
       table users
 
-      # LDAP user data
-      getter ldap : Ldap::User?
-
       has_one :teacher
       has_one :student
 
@@ -38,31 +35,6 @@ module Backend
       # User is admin
       column admin : Bool = false
 
-      # User's first name
-      def first_name : String
-        refresh_ldap.first_name
-      end
-
-      # User's last name
-      def last_name : String
-        refresh_ldap.last_name
-      end
-
-      # User's full name
-      def name : String
-        "#{first_name} #{last_name}"
-      end
-
-      # User's email
-      def email : String
-        refresh_ldap.email
-      end
-
-      # Refreshes LDAP user data
-      def refresh_ldap : Ldap::User
-        (@ldap ||= Ldap::User.from_json(Redis::CLIENT.get("ldap:user:#{@id}").as(String))).not_nil!
-      end
-
       validate :role, "needs to be a valid role" do |user|
         UserRole.parse(user.role).in?(UserRole.values)
       end
diff --git a/docker/backend/src/backend/ldap.cr b/docker/backend/src/backend/ldap.cr
index 18497ab..cd345f3 100644
--- a/docker/backend/src/backend/ldap.cr
+++ b/docker/backend/src/backend/ldap.cr
@@ -35,23 +35,6 @@ module Backend
       LDAP::Client.new(TCPSocket.new(Backend.config.ldap.host, Backend.config.ldap.port))
     end
 
-    # Queries the LDAP server for a user
-    #
-    # NOTE: Returns raw LDAP data
-    def raw_user(dn : String) : User::Raw
-      CLIENT.connection do |client|
-        client
-          .authenticate(Backend.config.ldap.bind_dn, Backend.config.ldap.bind_password)
-          .search(base: dn)
-          .first
-      end
-    end
-
-    # Queries the LDAP server for a user
-    def user(dn : String) : User
-      User.from_raw(raw_user(dn))
-    end
-
     # Checks if credentials are valid
     def authenticate?(dn : String, password : String) : Bool
       !!CLIENT.connection(&.authenticate(dn, password))
diff --git a/docker/backend/src/backend/ldap/user.cr b/docker/backend/src/backend/ldap/user.cr
index 4989490..692831e 100644
--- a/docker/backend/src/backend/ldap/user.cr
+++ b/docker/backend/src/backend/ldap/user.cr
@@ -39,6 +39,11 @@ module Backend
       def initialize(@first_name : String, @last_name : String, @email : String)
       end
 
+      # Name
+      def name : String
+        "#{first_name} #{last_name}"
+      end
+
       # Creates user data from LDAP entry
       def self.from_raw(raw : Raw) : self
         self.new(
@@ -47,6 +52,33 @@ module Backend
           email: raw["mail"].first
         )
       end
+
+      # Creates user data from LDAP DN entry
+      def self.from_dn(dn : String) : self
+        from_raw(
+          CLIENT.connection do |client|
+            client
+              .authenticate(Backend.config.ldap.bind_dn, Backend.config.ldap.bind_password)
+              .search(base: dn, attributes: %w(givenName sn mail))
+              .first
+          end
+        )
+      end
+
+      # Creates user data from LDAP username
+      def self.from_username(username : String) : self
+        from_dn(Ldap::Constructor.uid(username))
+      end
+
+      # Creates user data from DB entry
+      def self.from_db(user : Db::User) : self
+        from_username(user.username)
+      end
+
+      # Creates user data from DB entry index
+      def self.from_index(id : Int32) : self
+        from_db(Db::User.find!(id))
+      end
     end
   end
 end
diff --git a/docker/backend/src/backend/mailers/teacher_registration_mailer.cr b/docker/backend/src/backend/mailers/teacher_registration_mailer.cr
index 3cf46b8..7a9ee37 100644
--- a/docker/backend/src/backend/mailers/teacher_registration_mailer.cr
+++ b/docker/backend/src/backend/mailers/teacher_registration_mailer.cr
@@ -22,7 +22,7 @@ module Backend
         address email: Backend.config.smtp.username, name: Backend.config.smtp.name
       end
 
-      def initialize(user : Db::User)
+      def initialize(user : Ldap::User)
         to name: user.name, email: user.email
         subject "Mentorenwahl Lehrer Registrierung"
         text Kilt.render("#{__DIR__}/templates/teacher_registration_mailer.txt.ecr")
diff --git a/docker/backend/src/backend/worker/jobs/cache_ldap_user_job.cr b/docker/backend/src/backend/worker/jobs/cache_ldap_user_job.cr
index 8e43b30..2a2b8d9 100644
--- a/docker/backend/src/backend/worker/jobs/cache_ldap_user_job.cr
+++ b/docker/backend/src/backend/worker/jobs/cache_ldap_user_job.cr
@@ -19,16 +19,18 @@ module Backend
     module Jobs
       # Caches user data in redis cache
       class CacheLdapUserJob < Mosquito::QueuedJob
-        params id : Int64
+        params id : Int32
 
         # :ditto:
         def perform : Nil
           key = "ldap:user:#{id}"
           user = Db::User.find(id)
           if user
-            ldap_user = Ldap.user(Ldap::Constructor.uid(user.username))
-            Redis::CLIENT.set(key, ldap_user.to_json, (Backend.config.ldap.cache_refresh_interval * 2).minutes.to_i)
+            log "Caching user ##{id}..."
+            ldap_user = Ldap::User.from_username(user.username)
+            Redis::CLIENT.set(key, ldap_user.to_json)
           else
+            log "User ##{id} not found. Deleting cache..."
             Redis::CLIENT.del(key)
           end
         end
diff --git a/docker/backend/src/backend/worker/jobs/cache_ldap_users_job.cr b/docker/backend/src/backend/worker/jobs/cache_ldap_users_job.cr
index 7dcf50e..2562e77 100644
--- a/docker/backend/src/backend/worker/jobs/cache_ldap_users_job.cr
+++ b/docker/backend/src/backend/worker/jobs/cache_ldap_users_job.cr
@@ -24,10 +24,16 @@ module Backend
         # :ditto:
         def perform : Nil
           Redis::CLIENT.keys("ldap:user:*")
-            .map(&.as(String).split(":")[2].to_i64)
-            .concat(Db::User.all.map(&.id.not_nil!))
+            .map(&.as(String).split(":")[2].to_i)
+            .concat(Db::User.all.map(&.id.not_nil!.to_i))
             .uniq!
-            .each { |id| CacheLdapUserJob.new(id).enqueue }
+            .each do |id|
+              spawn do
+                CacheLdapUserJob.new(id).enqueue
+              end
+            end
+
+          Fiber.yield
         end
       end
     end
diff --git a/docker/backend/src/backend/worker/jobs/send_teachers_registration_email_job.cr b/docker/backend/src/backend/worker/jobs/send_teachers_registration_email_job.cr
index 0ca9548..99c98d4 100644
--- a/docker/backend/src/backend/worker/jobs/send_teachers_registration_email_job.cr
+++ b/docker/backend/src/backend/worker/jobs/send_teachers_registration_email_job.cr
@@ -32,8 +32,9 @@ module Backend
                 fail
               end
 
-              log "Sending teacher registration email to #{user.email} (#{user.id})"
-              Mailers::TeacherRegistrationMailer.new(user).deliver
+              ldap_user = Ldap::User.from_username(user.username)
+              log "Sending teacher registration email to #{ldap_user.email} ##{user.id}"
+              Mailers::TeacherRegistrationMailer.new(ldap_user).deliver
 
               channel.send(nil)
             end
diff --git a/docker/backend/src/cli/backend.cr b/docker/backend/src/cli/backend.cr
index 62e94b0..be59c09 100644
--- a/docker/backend/src/cli/backend.cr
+++ b/docker/backend/src/cli/backend.cr
@@ -84,7 +84,7 @@ cli = Commander::Command.new do |cmd|
       abort unless (gets(chomp: true) || "").strip.downcase == "y"
 
       user = Backend::Db::User.create!(username: username, role: role.to_s, admin: opts.bool["admin"])
-      Backend::Worker::Jobs::CacheLdapUserJob.new(user.id.not_nil!).enqueue
+      Backend::Worker::Jobs::CacheLdapUserJob.new(user.id.not_nil!.to_i).enqueue
 
       puts "Done!"