SMTP is not a requirement to send emails, but I always recommend to use SMTP because the PHP Mail function does not have the option to authenticate the email sender, that's why your email messages are going to the SPAM folder.
Due to the fact that PHP Mail function does not have authentication, anyone with basic PHP knowledge can use PHP Mail function to send email as anyone@anydomain. Therefore, most mail servers and mail clients are imposing strict rules against unauthenticated emails. Even though you noticed it just after the update, the mail server might have been sending your emails to the spam folder for a while or it might be a coincidence. I assure you it has nothing to do with the lastest Contact Enhanced version.
Please read item #5 in the article below, which explains why you should be using SMTP:
Why emails are not being sent, never received or sent to SPAM folder? 5-Do you need authentication?
When you send email from your mail program or Joomla, you need to provide a password for outgoing mail (outgoing mail authentication?). If you are unsure because you set up your mail a long time ago, the best thing to do is ask your host. This is usually required because most mail servers nowadays have implemented DMARC policy in order to help reduce the potential for email-based abuse. For more information please go to the DMARC website.
Our extensions use Joomla framework and configuration to send emails and some mail servers will not work correctly with Sendmail or PHP Mailer because of the DMARC policy mentioned above. Therefore these servers require that unauthenticated emails must be sent from or to an email address @your-domain.com, or do not allow unauthenticated emails. It seems to be your case, specially if only the copy message is sent.
We always recommend to set the mailer to SMTP in the Joomla Global Configuration under the Server tab. This will avoid many mail problems, including your contact message be marked as SPAM.
Go to Global Configuration and set these options below accordingly to your server. If you are unsure how to do it, please contact your web hosting provider and he will be able to give you this information:
Mailer: SMTP Server
SMTP Authentication:
SMTP Security:
SMTP Port:
SMTP Username:
SMTP Password:
SMTP Host:
Only the Sender Email account configured in Joomla Global Configuration has to be a valid/real email account (with password). It will authenticate and then send emails as another email from your own domain. In other words, you do not need SMTP settings for your Contact Enhanced Contacts. Therefore your Contacts can still have forwarders in the email field. The Sender email (Authenticated) does not have to match the mail FROM field (in most cases, continue reading
).
Something that I wouldn't worry about right now (in 2020), but I'll mention because there I want to give all the information you need:
there are a few mail servers that require the FROM email address match the Sender email (from the SMTP settings). In this case, you would have to not only properly configure
SMTP in
Joomla Global Configuration but also set the
Email sender option in Contact Enhanced Component Options (under the
Contact Form tab) to
Use Global. Again, I rarely see this and this is probably NOT your case.
Let me know if you have any further questions.
Best regards,