Using smtp for sending emails, do I need to use a strong server?

Hello, if I use stmp to send emails through a custom contact (email@mydomain.com) do I need a strong server for submissions? Or will I continue to use the JotFrm server for submissions?

As far as I understood your question, I suppose that you refer to the limit of emails can be sent via your custom smtp server. If you are using Google SMTP Server to send emails, please make sure that you have followed the steps on this guide

How-to-Use-Your-Gmail-Account-as-Your-Email-Sender-via-SMTP.

You will need to turn off something in your Google account to allow the 3rd party apps to use your SMTP without restrictions.

In the other cases, if you face any problems or limitations, you can always get back to using JotForm servers again. You can even change the Sender Name at the emails sent. 

Setting-up-an-Autoresponder-Email

Hope this information helps! But, let us know if you need further assistance.

Perfect, it's about the shipping limit.

However I will not use Gmail, I will use a third party website hosting server. In fact, I just want you to show that the email that sent the information was from my site (email@mydomain.com) and not noreply@jotform.com.

In this case should I use SMTP?

Yes, for the purpose you described, you will need to set up smtp or verified email as a sender.  Your respondents will not see noreply@jotform.com after that. 

So, my recommendation would be to try using your custom smtp. I believe that the worst thing that can happen, is that your Autoresponds will be somewhat delayed. But I am not 100% sure what workload should be to cause that. As I have mentioned earlier, you can always get back to our email servers. 

How-to-Setup-SMTP-for-a-Form

Good luck! And let us know if you need any other help as to your JotForms.