Sending Customer statements takes about 3 days. Is there a way to make it faster/easier to send out?

Good Day,

One of my clients is sending their statements via email to their customers, using multiple groups/sales reps if not all of them at once.

However, the process runs over 3 days to complete, so much so that the user is logging in via RDP to different machine just to send out the statements, allowing her to continue with her work on her normal workstation.

Is there a way to streamline and run it faster than this?

Evolution v10.1.3.007

All customers with valid email addresses have the "Email Statement" checkbox selected.

Using SMTP Server via Microsoft 365.

Test email received and the Test Connection for the SMTP connection is both successful.

Thank you.

Kobus