diff --git a/frontend/src/components/GddSend/TransactionForm.vue b/frontend/src/components/GddSend/TransactionForm.vue
index 41fb400e7..2f369c9ca 100644
--- a/frontend/src/components/GddSend/TransactionForm.vue
+++ b/frontend/src/components/GddSend/TransactionForm.vue
@@ -125,108 +125,108 @@
   </div>
 </template>
 <script>
- import { SEND_TYPES } from '@/pages/Send'
- import InputIdentifier from '@/components/Inputs/InputIdentifier'
- import InputAmount from '@/components/Inputs/InputAmount'
- import InputTextarea from '@/components/Inputs/InputTextarea'
- import { user as userQuery } from '@/graphql/queries'
- import { isEmpty } from 'lodash'
+import { SEND_TYPES } from '@/pages/Send'
+import InputIdentifier from '@/components/Inputs/InputIdentifier'
+import InputAmount from '@/components/Inputs/InputAmount'
+import InputTextarea from '@/components/Inputs/InputTextarea'
+import { user as userQuery } from '@/graphql/queries'
+import { isEmpty } from 'lodash'
 
- export default {
-   name: 'TransactionForm',
-   components: {
-     InputIdentifier,
-     InputAmount,
-     InputTextarea,
-   },
-   props: {
-     balance: { type: Number, default: 0 },
-     identifier: { type: String, default: '' },
-     amount: { type: Number, default: 0 },
-     memo: { type: String, default: '' },
-     selected: { type: String, default: 'send' },
-   },
-   data() {
-     return {
-       form: {
-         identifier: this.identifier,
-         amount: this.amount ? String(this.amount) : '',
-         memo: this.memo,
-       },
-       radioSelected: this.selected,
-       userName: '',
-     }
-   },
-   methods: {
-     onValidation() {
-       this.$refs.formValidator.validate()
-     },
-     onSubmit() {
-       if (this.gradidoID) this.form.identifier = this.gradidoID
-       this.$emit('set-transaction', {
-         selected: this.radioSelected,
-         identifier: this.form.identifier,
-         amount: Number(this.form.amount.replace(',', '.')),
-         memo: this.form.memo,
-         userName: this.userName,
-       })
-     },
-     onReset(event) {
-       event.preventDefault()
-       this.form.identifier = ''
-       this.form.amount = ''
-       this.form.memo = ''
-       this.$refs.formValidator.validate()
-       if (this.$route.query && !isEmpty(this.$route.query))
-         this.$router.replace({ query: undefined })
-     },
-   },
-   apollo: {
-     UserName: {
-       query() {
-         return userQuery
-       },
-       fetchPolicy: 'network-only',
-       variables() {
-         return { identifier: this.gradidoID }
-       },
-       skip() {
-         return !this.gradidoID
-       },
-       update({ user }) {
-         this.userName = `${user.firstName} ${user.lastName}`
-       },
-       error({ message }) {
-         this.toastError(message)
-       },
-     },
-   },
-   computed: {
-     disabled() {
-       if (
-         this.form.identifier.length > 5 &&
-         parseInt(this.form.amount) <= parseInt(this.balance) &&
-         this.form.memo.length > 5 &&
-         this.form.memo.length <= 255
-       ) {
-         return false
-       }
-       return true
-     },
-     isBalanceDisabled() {
-       return this.balance <= 0 ? 'disabled' : false
-     },
-     sendTypes() {
-       return SEND_TYPES
-     },
-     gradidoID() {
-       return this.$route.query && this.$route.query.gradidoID
-     },
-   },
-   mounted() {
-     if (this.form.identifier !== '') this.$refs.formValidator.validate()
-   },
- }
+export default {
+  name: 'TransactionForm',
+  components: {
+    InputIdentifier,
+    InputAmount,
+    InputTextarea,
+  },
+  props: {
+    balance: { type: Number, default: 0 },
+    identifier: { type: String, default: '' },
+    amount: { type: Number, default: 0 },
+    memo: { type: String, default: '' },
+    selected: { type: String, default: 'send' },
+  },
+  data() {
+    return {
+      form: {
+        identifier: this.identifier,
+        amount: this.amount ? String(this.amount) : '',
+        memo: this.memo,
+      },
+      radioSelected: this.selected,
+      userName: '',
+    }
+  },
+  methods: {
+    onValidation() {
+      this.$refs.formValidator.validate()
+    },
+    onSubmit() {
+      if (this.gradidoID) this.form.identifier = this.gradidoID
+      this.$emit('set-transaction', {
+        selected: this.radioSelected,
+        identifier: this.form.identifier,
+        amount: Number(this.form.amount.replace(',', '.')),
+        memo: this.form.memo,
+        userName: this.userName,
+      })
+    },
+    onReset(event) {
+      event.preventDefault()
+      this.form.identifier = ''
+      this.form.amount = ''
+      this.form.memo = ''
+      this.$refs.formValidator.validate()
+      if (this.$route.query && !isEmpty(this.$route.query))
+        this.$router.replace({ query: undefined })
+    },
+  },
+  apollo: {
+    UserName: {
+      query() {
+        return userQuery
+      },
+      fetchPolicy: 'network-only',
+      variables() {
+        return { identifier: this.gradidoID }
+      },
+      skip() {
+        return !this.gradidoID
+      },
+      update({ user }) {
+        this.userName = `${user.firstName} ${user.lastName}`
+      },
+      error({ message }) {
+        this.toastError(message)
+      },
+    },
+  },
+  computed: {
+    disabled() {
+      if (
+        this.form.identifier.length > 5 &&
+        parseInt(this.form.amount) <= parseInt(this.balance) &&
+        this.form.memo.length > 5 &&
+        this.form.memo.length <= 255
+      ) {
+        return false
+      }
+      return true
+    },
+    isBalanceDisabled() {
+      return this.balance <= 0 ? 'disabled' : false
+    },
+    sendTypes() {
+      return SEND_TYPES
+    },
+    gradidoID() {
+      return this.$route.query && this.$route.query.gradidoID
+    },
+  },
+  mounted() {
+    if (this.form.identifier !== '') this.$refs.formValidator.validate()
+  },
+}
 </script>
 <style>
 span.errors {
diff --git a/frontend/src/components/Inputs/InputIdentifier.vue b/frontend/src/components/Inputs/InputIdentifier.vue
index 84ed9eaee..d598dad1c 100644
--- a/frontend/src/components/Inputs/InputIdentifier.vue
+++ b/frontend/src/components/Inputs/InputIdentifier.vue
@@ -27,43 +27,43 @@
   </validation-provider>
 </template>
 <script>
- export default {
-   name: 'InputEmail',
-   props: {
-     rules: {
-       default: () => {
-         return {
-           required: true,
-           validIdentifier: true,
-         }
-       },
-     },
-     name: { type: String, required: true },
-     label: { type: String, required: true },
-     placeholder: { type: String, required: true },
-     value: { type: String, required: true },
-     disabled: { type: Boolean, required: false, default: false },
-   },
-   data() {
-     return {
-       currentValue: this.value,
-     }
-   },
-   computed: {
-     labelFor() {
-       return this.name + '-input-field'
-     },
-   },
-   watch: {
-     currentValue() {
-       this.$emit('input', this.currentValue)
-     },
-     value() {
-       if (this.value !== this.currentValue) {
-         this.currentValue = this.value
-       }
-       this.$emit('onValidation')
-     },
-   },
- }
+export default {
+  name: 'InputEmail',
+  props: {
+    rules: {
+      default: () => {
+        return {
+          required: true,
+          validIdentifier: true,
+        }
+      },
+    },
+    name: { type: String, required: true },
+    label: { type: String, required: true },
+    placeholder: { type: String, required: true },
+    value: { type: String, required: true },
+    disabled: { type: Boolean, required: false, default: false },
+  },
+  data() {
+    return {
+      currentValue: this.value,
+    }
+  },
+  computed: {
+    labelFor() {
+      return this.name + '-input-field'
+    },
+  },
+  watch: {
+    currentValue() {
+      this.$emit('input', this.currentValue)
+    },
+    value() {
+      if (this.value !== this.currentValue) {
+        this.currentValue = this.value
+      }
+      this.$emit('onValidation')
+    },
+  },
+}
 </script>
diff --git a/frontend/src/validation-rules.js b/frontend/src/validation-rules.js
index d27d1f6fb..a23d69215 100644
--- a/frontend/src/validation-rules.js
+++ b/frontend/src/validation-rules.js
@@ -5,9 +5,10 @@ import { checkUsername } from '@/graphql/queries'
 import { validate as validateUuid, version as versionUuid } from 'uuid'
 
 // taken from vee-validate
+// eslint-disable-next-line no-useless-escape
 const emailRegex = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/
 
-const usernameRegex = /^(?=.{3,20}$)[a-zA-Z0-9]+(?:[_-][a-zA-Z0-9])*$/
+const usernameRegex = /^(?=.{3,20}$)[a-zA-Z0-9]+(?:[_-][a-zA-Z0-9]+?)*$/
 
 export const loadAllRules = (i18nCallback, apollo) => {
   configure({
@@ -147,7 +148,7 @@ export const loadAllRules = (i18nCallback, apollo) => {
 
   extend('usernameUnique', {
     validate(value) {
-      if (value.match(/^(?=.{3,20}$)[a-zA-Z0-9]+(?:[_-][a-zA-Z0-9]+?)*$/)) {
+      if (value.match(usernameRegex)) {
         return apollo
           .query({
             query: checkUsername,
@@ -169,8 +170,8 @@ export const loadAllRules = (i18nCallback, apollo) => {
     validate(value) {
       const isEmail = !!value.match(emailRegex)
       const isUsername = !!value.match(usernameRegex)
-      // const isGradidoId = validateUuid(value) && versionUuid(value) === 4
-      return isEmail || isUsername // || isGradidoId
+      const isGradidoId = validateUuid(value) && versionUuid(value) === 4
+      return isEmail || isUsername || isGradidoId
     },
     message: (_, values) => i18nCallback.t('form.validation.valid-identifier', values),
   })