There are many reasons for email communication errors. Example: In LUCY, emails appeared to be sent to your recipients. But sometimes emails never arrive or arrive very late. In this case, there are a few issues you can check:
Please also take a look at the Postfix mail log to get a more detailed output.
There are a few possible scenario's:
If the test mail arrives you know that the SMTP communication works and LUCY's IP is not filtered by any 3rd Party product. Therefore you experience a configuration issue in the campaign which causes the mail to get filtered (like using a spoofed sender domain which has an SPF record, using a sender domain that points to a different MX record or has no valid MX record at all or creating a campaign that gets filtered because of the SPAM score). Also make sure you even created a message template in the campaign).
If the test mail does not go through: make sure port 25 is opened on your router/firewall and mails do not get filtered by SPAM filters. In case the firewall configuration is not allowing LUCY to send mails, you might also configure LUCY to use an external mail server. See using_an_external_mail_server_or_web_proxy. Also please investigate your configuration
Yes - please consult this chapter.