What I think you are saying is that your Form Plugin is sending the results of a form submission to [email protected]
It is also sending a confirmation message to the form submitter ([email protected])
You are saying that the user is getting his confirmation before the actual data of the form has reached [email protected]
That would be a feature or behaviour of whatever form App/Plugin you are using, not Post SMTP.
Post SMTP simply replaces the WordPress WP-Mail function with a much better mail method.
It has no knowledge of what is being sent or when to send it.
That is determined by WordPress Core or the WordPress Plugins.
i.e.
Form Plugin Does Stuff
Form Plugin Does more Stuff
Form Plugin Does more Stuff
Form Plugin sends Form Submission Data
Form Plugin sends Confirmation Mail
Form Plugin finishes
At no point does the Form Plugin have any knowledge that Post SMTP is involved, and likewise, Post SMTP doesn’t know that a Form plugin sent a mail.
There are also many factors in the chain that could affect the times.
i.e. You are using the same SMTP account to send the email. Your Form Plugin is likely to send the emails one after the other so any delay here would be minimal.
Unless you control the mail server where your submissions are sent, you don’t know how long it takes your inbound submissions to transit through it’s system. And if say you are using Microsoft Outlook to receive your emails, and that is set to only receive emails once per hour, you might have to wait 59 mins for the ‘new mail’ to pop up on your screen. Even if you have your mail client set to notify you immediately when a new email arrives (IMAP method), you still have no control over how long it takes the email to transit through their mail servers before it gets to your inbox.
One possibility if you are using a Form module like Gravity is that you can override the forms notification behaviour and introduce a delay such that the completed form is sent on submit, but the confirmation email is delayed (a finite period) before being sent rather than being automatic as it is at the moment. You could use the WP Cron to set up an event that occurs in the future to send the user confirmation. Or something along those lines.
But Post SMTP can’t help you with any of this. It merely sends what it is told (the mail) to where it is told (the recipient) using what method it is told (SMTP server/Gmail API /SendGrid).
Only thing Post SMTP can control is the method.
The what and when is up to WordPress / Plugins.
