we are emailing the receipts of last year's contributions. From "find contributions" we select "Thank-you letters - print or email" and then "Send emails where possible. Generate printable PDFs for contacts who cannot receive email.".
I thought it was using the CiviMail component to send (and its configurations, like Mailer Batch Limit, Mailer Throttle Time), but emails are sent immediately, occupying a lot of memory resources. And my SMTP server rejects them as spam.
Have I forgotten a configuration? Or is it the behaviour for this process? Or is there another way to send receipts of last year's contributions? Or should I use SparkPost which distributes the email delivery?
Any help is appreciated.