How to save the additional checkbox in Porto Theme’s custom Login form?

I’m truly newbie to Magento 2 developer, and I’m currently facing a problem that I can’t amazing how to solve the problem that describes as below:

The problem:
I’ve added a checkbox (Tilmeld nyhedsbrev) in English (Sign Up for Newsletter) into the Porto Theme’s login form. Please take a look at the attachment image for further information.

The question is:
If a customer marked the checkbox (checked=true) the click the LOG IND (submit button) button, well, then… how do I save the customer’s email into Magento 2 Customer newsletter module database?

Here is the code for that action:

escapeHtml(__(‘Registered Customers’)) ?>

escapeUrl($block->getPostActionUrl()) ?>”
method=”post”
id=”login-form”
data-mage-init='{“validation”:{}}’>
[![enter image description here][1]][1]getBlockHtml(‘formkey’) ?>
escapeHtml(__(‘* Required Fields’)) ?>”>
escapeHtml(__(‘If you have an account, sign in with your email address.’)) ?>

                <div class="field email required">
                    <label class="label" for="email"><span><?= $block->escapeHtml(__('Email')) ?></span></label>
                    <div class="control">
                        <input name="login[username]" value="<?= $block->escapeHtmlAttr($block->getUsername()) ?>" <?php if ($block->isAutocompleteDisabled()) : ?> autocomplete="off"<?php endif; ?> id="email" type="email" class="input-text line-height-xl" title="<?= $block->escapeHtmlAttr(__('Email')) ?>" data-mage-init='{"mage/trim-input":{}}' data-validate="{required:true, 'validate-email':true}">
                    </div>
                </div>

                <div class="field password required">
                    <label for="pass" class="label"><span><?= $block->escapeHtml(__('Password')) ?></span></label>
                    <div class="control">
                        <input name="login[password]" type="password" <?php if ($block->isAutocompleteDisabled()) : ?> autocomplete="off"<?php endif; ?> class="input-text line-height-xl" id="pass" title="<?= $block->escapeHtmlAttr(__('Password')) ?>" data-validate="{required:true}">
                    </div>
                </div>
                
                <?= $block->getChildHtml('form_additional_info') ?>
                <div class="field">
                    <a class="action remind" href="<?= $block->escapeUrl($block->getForgotPasswordUrl()) ?>"><span><?= $block->escapeHtml(__('Forgot Your Password?')) ?></span></a>
                </div>

                <div class="actions-toolbar">
                    <div class="primary"><button type="submit" class="action login primary btn-v-dark py-3 text-md w-100" name="send" id="send2"><span><?= $block->escapeHtml(__('Sign In')) ?></span></button></div>
                    <div class="secondary">
                        <a href="/customer/account/create/" class="action create primary btn-v-dark py-3 text-md w-100"><span><?= $block->escapeHtml(__('Create an Account')) ?></span></a>
                    </div>
                        
                    <style>
                        .customer-account-login .action.create {
                            display: none;
                        }
                    </style>
                </div>

                <div class="field choice login-newsletter">
                    <input 
                        type="checkbox" 
                        name="is_subscribed" 
                        id="login-newsletter" 
                        value="1" 
                        title="<?= $block->escapeHtmlAttr(__('Sign Up for Newsletter')) ?>"
                        <?php /* default unchecked */?>
                        class="checkbox">
                    <label for="login-newsletter" class="label"><span><?= $block->escapeHtml(__('Sign Up for Newsletter')) ?></span></label>
                </div>
                
          </fieldset>
      </form>
  </div>