I am trying to send CiviContribute thank you letters by email using this workflow:
Find Contributions > Actions > Thank-you letters - print or email
Invariably, I get the following error:
An error occurred when CiviCRM attempted to send an email (via SMTP). If you received this error after submitting on online contribution or event registration - the transaction was completed, but we were unable to send the email receipt. The mail library returned the following error message: The SparkPost service is unavailable due to a sending error, and the backup mailer is not enabled or not configured. This is probably related to a problem in your Outbound Email Settings (Administer CiviCRM » System Settings » Outbound Email), OR the FROM email address specifically configured for your contribution page or event. Possible causes are: Your Sendmail path is incorrect. Your Sendmail argument is incorrect. The FROM Email Address configured for this feature may not be a valid sender based on your email service provider rules.
I am using CiviDesk SparkPost for my emails. I am able to successfully send transactional and CiviMail emails. My email address works just fine for these, and it is configured in the FROM email addresses. I am a site administrator, so full permissions.
Any clues? Thanks for helping me troubleshoot.
Update: I tested again using this workflow:
Find Contributions > Actions > Email - send now
And the Thank You emails went out without incident.
So it seems to me that my email setup is perfectly fine. This must be an issue with CiviContribute and the Thank You Letter workflow.