MailChimp - MailChimp is the best way to design, send, and share email newsletters.
Mobbin - Latest mobile design patterns & elements library
Constant Contact - Constant Contact offers email marketing, social media marketing, online survey, event marketing, digital storefronts, and local deals tools.
pttrns - iPhone and iPad user interface patterns
Brevo - Innovative online Email Marketing solution to manage your contacts, create & send your newsletters and track your results. More than 80 000 clients. Best prices and attractive features.
Page Flows - User flow design inspiration for mobile & desktop