[MM-40917] - Inactive Server Email Notification (#19374)

* [MM-40917] - Inactive Server Email Notification

* add email template

* make store layers

* add some store tests

* fix translations

* fix logic

* improve

* fix lint

* feedback-impl

* fix wrong text

* optimize queries

* move feature flag check

* feedback impl-1

* add line

* feedback impl

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/email/email.go

@@ -762,6 +762,39 @@ func (es *Service) SendAtUserLimitWarningEmail(email string, locale string, site
 	return true, nil
 }
 
+func (es *Service) SendLicenseInactivityEmail(email, name, locale, siteURL string) error {
+	T := i18n.GetUserTranslations(locale)
+	subject := T("api.templates.server_inactivity_subject")
+	data := es.NewEmailTemplateData(locale)
+	data.Props["SiteURL"] = siteURL
+	data.Props["Title"] = T("api.templates.server_inactivity_title")
+	data.Props["SubTitle"] = T("api.templates.server_inactivity_subtitle", map[string]interface{}{"Name": name})
+	data.Props["InfoBullet"] = T("api.templates.server_inactivity_info_bullet")
+	data.Props["InfoBullet1"] = T("api.templates.server_inactivity_info_bullet1")
+	data.Props["InfoBullet2"] = T("api.templates.server_inactivity_info_bullet2")
+	data.Props["Info"] = T("api.templates.server_inactivity_info")
+	data.Props["EmailUs"] = T("api.templates.email_us_anytime_at")
+	data.Props["QuestionTitle"] = T("api.templates.questions_footer.title")
+	data.Props["QuestionInfo"] = T("api.templates.questions_footer.info")
+	data.Props["Button"] = T("api.templates.server_inactivity_button")
+	data.Props["SupportEmail"] = "feedback@mattermost.com"
+	data.Props["ButtonURL"] = siteURL
+	data.Props["Channels"] = T("Channels")
+	data.Props["Playbooks"] = T("Playbooks")
+	data.Props["Boards"] = T("Boards")
+
+	body, err := es.templatesContainer.RenderToString("inactivity_body", data)
+	if err != nil {
+		return err
+	}
+
+	if err := es.sendMail(email, subject, body); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func (es *Service) SendLicenseUpForRenewalEmail(email, name, locale, siteURL, renewalLink string, daysToExpiration int) error {
 	T := i18n.GetUserTranslations(locale)
 	subject := T("api.templates.license_up_for_renewal_subject")
@@ -775,6 +808,7 @@ func (es *Service) SendLicenseUpForRenewalEmail(email, name, locale, siteURL, re
 	data.Props["Button"] = T("api.templates.license_up_for_renewal_renew_now")
 	data.Props["ButtonURL"] = renewalLink
 	data.Props["QuestionTitle"] = T("api.templates.questions_footer.title")
+	data.Props["SupportEmail"] = "feedback@mattermost.com"
 	data.Props["QuestionInfo"] = T("api.templates.questions_footer.info")
 
 	body, err := es.templatesContainer.RenderToString("license_up_for_renewal", data)