Vodafone has closed all of its domain, email and web services, at the end of April 2019.
If Vodafone are your provider for any of these services, you will need to move to a new provider as you will no longer be able to send emails using those Vodafone credentials.
The emails will look like they have successfully sent from the Infusion queued emails screen, but the email will not be received by the recipient.
This information will need to be updated in Admin / Manage Email Defaults screen.
For more information see https://www.vodafone.co.nz/broadband/domains-and-hosting/