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How to fix “Required SMTP STARTTLS not supported” error
How to fix “Required SMTP STARTTLS not supported” error

Learn what to do if you hit this error when sending emails through LeadSimple.

Will Rosa avatar
Written by Will Rosa
Updated over a week ago

See an error message saying "Required SMTP STARTTLS not supported" when trying to send an email from LeadSimple?

Reconnect your email account to LeadSimple and the error should resolve itself. Use this updated information if asked while reconnecting:

  • IMAP host:

  • IMAP port: 993

  • SMTP host:

  • SMTP port: 465

  • Username/email: your email address, e.g.

  • Password: the password you use to log into your email account

Reach out to us at if you have any questions!

Technical note: this error is due to a recent change by Rackspace Email where they stopped supporting SMTP connections via 587 (Port 465 should be used instead as seen above.)

How do I know if I’m using Rackspace Email?

  1. Type your email domain (the part after @, e.g. under “Name” and hit Enter.

  2. If results include “” and “”, it means you’re using Rackspace Email.

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