add MFA, user web mail portal

internal/webui/templates/edit_mailbox.html

@@ -21,6 +21,11 @@
                         <label for="quota_gb" class="form-label">Storage Quota (GB)</label>
                         <input type="number" class="form-control" id="quota_gb" name="quota_gb" min="0.1" step="0.1" value="{{printf "%.2f" .quota_gb}}">
                     </div>
+                    <div class="mb-3 form-check">
+                        <input type="checkbox" class="form-check-input" id="mfa_exempt" name="mfa_exempt" {{if .mailbox.MFAExempt}}checked{{end}}>
+                        <label class="form-check-label" for="mfa_exempt">Exempt this mailbox from mandatory MFA</label>
+                        <div class="form-text">Only relevant if "Enforce MFA for Mailboxes" is turned on in Server Settings.</div>
+                    </div>
                     <div class="d-flex gap-2">
                         <button type="submit" class="btn btn-primary"><i class="bi bi-check-lg me-1"></i>Update Mailbox</button>
                         <a href="/pymta-manager/mailboxes" class="btn btn-secondary"><i class="bi bi-x-lg me-1"></i>Cancel</a>