I decided to try this form out to replace an older less flexible one that was used before I started. I installed the form via the package installer and did the simple implementation of;

<umbraco:Macro FileLocation="~/macroScripts/CultivContactForm.cshtml" MailFrom="support@***.com" runat="server" />

I tried sending out an email. Now the SMTP settings are already set in the web.config, which the previous form uses fine.

However when I try submitting the contact from it disappears and no email. I checked the umbraco log in the DB and had the following error;

 Error creating or sending contact mail, check if there is a mailFrom property on your document and that it has a value, or specify a MailFrom parameter on the macro call exception: System.Net.Mail.SmtpFailedRecipientException: Mailbox unavailable. The server response was: must be authenticated

I checked and messed with the SMTP settings but with no luck and the implementation of the form is it's default state which I would assume doesn't contain any issues. 

One thing that might be worth noting is our Umbraco package is actually v4.7.0 but I followed a guide to update the razor engine to 4.7.1 since I was told when someone tried updating the site many errors occurred. 

I'm not sure if the issue is with the setup or perhaps our version of Umbraco but any advice would be appreciated.