Mail is a tempting line item for anyone cutting fixed costs. You already have a server, so sending from it looks free. But what you are really buying with email is arrival, not transmission, and those two things are priced very differently.
What sending it yourself actually costs
Pushing mail out of your own server is the easy part. The hard part is getting the receiving side to believe it. To fight spam, mail providers verify senders in several ways, and anything that fails those checks is filed as spam or discarded without a word.
The absence of any way to notice failures is the dangerous part. The form works, the screen says “message sent”, and nothing arrives — and you find out days later from a customer’s phone call. That loss appears on no price list anywhere.
A realistic order for a founder
The short answer: hand sending over, but start in the free tier. Most sending services offer a free allowance for small volumes, so while enquiries are a handful a day this costs nothing in practice.
Starting with the SMTP of the mailbox you already pay for is perfectly sound. It is the simplest to configure and delivery is stable. The catch is a daily sending limit per account, which you will hit quickly if you ever send a newsletter to a list.
Move to a dedicated sending service before you reach that ceiling. What matters there is not the price but the fact that everything is logged. When an enquiry does not appear you can tell whether it was never sent or sent and never received, and that single distinction cuts the time to a fix dramatically.
Do not mix the two kinds of mail
One more place where cost is decided. The mail your site sends divides into two categories with quite different characters: transactional mail that must reach one specific person — enquiry alerts, password resets, receipts — and marketing mail that goes out to many at once, such as newsletters and promotions.
Sending both down one path is risky. Unsubscribes and complaints from marketing mail erode your sending reputation, and the fallout files the enquiry alerts that absolutely must arrive into spam alongside them. Split the paths and a marketing problem leaves your lifeline untouched.
Whichever path you take, set the three domain authentication records. Your sending service hands you the exact values to paste into DNS, and it is the single largest improvement in deliverability available for nothing.
Server and mail material lives in the Servers & infrastructure archive, and how to decide which tools deserve a subscription was covered in what free covers. Sorting the sending path out as part of wider infrastructure work is included in our optimization program.
Next part
Backups next: how far a nearly-free backup strategy really reaches, and how to judge whether you can live with where it stops.