Mailtrap.io
Fake SMTP server for development, free plan with one inbox, 100 messages, no team member, two emails/second, no forward rules
trashmail.com
Free disposable email addresses with forwarding and automatic address expiration
TempMailDetector.com
Verify up to 200 emails a month for free and see if an email is temporary or not
inboxkitten.com
Free temporary/disposable email inbox, with up to 3-day email auto-deletes. Open source and can be self-hosted
MailerSend.com
Email API, SMTP, 3,000 emails/month free for transactional emails
verimail.io
Bulk and API email verification service. 100 free verifications/month
temp-mail.io
Free disposable temporary email service with multiple emails at once and forwarding
Mail7.io
Free Temp Email Addresses for QA Developers. Create email addresses instantly using Web Interface or API
dkimvalidator.com
Test if the email's DNS/SPF/DKIM/DMARC settings are correct, free service by roundsphere.com
FormSpree
Receive form submissions by email
Hunter.io
Email lead and validation APIs
mailchannels.com
Email API with REST API and SMTP integrations, free for upto 3,000 emails/month