Mailwarm - The email warm-up tool.
Really Good Emails - A large collection of good product email design.
Murlist Email Warmup - Improve sender reputation on autopilot
Good Sales Emails - Best sales emails from great companies
MailReach.co - The #1 email warming service to improve your deliverability by generating realistic and meaningful engagement to your emails. Easy-to-use solution to help you land in the main inbox instead of the spam folder.
Great Email Copy - A dose of emails from around the web.