sendmail not able to send to specific e-mail address
I'm running an EC2 with (bitnami for wordpress) and have sendmail configured.
No matter if using my own php written forms or now contact form 7 plugin for wordpress there is one specific address (the clients mail address) that simply won't receive the mails from the forms.
I tested with multiple addresses of myself and I always get all the mails. As soon as I swith to the clients mail-address though they don't get the form mails, not even in the Spam-Folder.
What could be a potential reason?
I thought maybe the server doens't like the same sender and receiver address as the sending address in contact form 7 is info@website.at and the receiver is info@website.at … but I also changed that and tested, no difference.
here is the log file, but I'm unable to interpret that properly.
You should be very cautious about sending the email directly from an EC2, many email providers will actually block emails that come from the AWS EC2 ranges. This exists to prevent an EC2 host being used to send spam/spoof emails.
Additionally Bitnami mention in there documentation the below.
We recommend using an external SMTP server to send email from EC2 instances, due to AWS limitations on EC2 machines. For PHP applications, read the instructions on how to send emails using Gmail or using Amazon Simple Email Service (SES).
By using an external SMTP server combined with adding a valid SPF record you should be able to reduce the chance of emails not making it through to the client in addition to not being labelled as spam either.