MonthHi, we're currently using %Net.SMTP for sending mails, which is not performing well in terms of delivery speed - I digged into the code and I can see that we're crafting a %Net.MailMessage for every recipient of the same mail, instead of adding all the recipients to the list property "To"
However we cannot do this, because the sender address (Sender property) we use to track bounce mails by adding a unique ID to the sender address for every recipient.