SMTP error on emailed Report

From what I can say based on the information provided, it seems that the email is Invalid. Have you tried sending an email to the same address from a different email server like outlook just to verify if the email goes through?

If you have and the email is successfully delivered, can you confirm from the AWS side if the email was delivered and rejected for some reason?

We have seen some SMTP servers rejecting emails due to rate limits restrictions and it is a proper way to prevent overloading systems and mailboxes. (DDoSAttacks). Please refer to our knowledge base article Can't Send Email to Gmail?

If after those tests you still believe the issue could be related with PRTG even though other emails work fine and the problem is just with one account, we will require more details and screenshots to have a better understanding and provide a solution to your issue.

I will suggest you to open a support request directly from the PRTG Web interface, with this same description and provide screenshots of the error you are seeing along with the SMTP Notification Delivery configuration and the error message and the failing email account for further investigation.

Please notice that the built-in mail option uses the MX recordto send the emails. As such, such a record must exist and must connect to a mail relay server in order for this option to work. If you have such a connection, please check the same and the DNS settings, to make sure that the settings are properly defined in such a way that PRTG would also be able to connect to the mail relay server defined.

The MX record would already have to be configured within your network, this is not a PRTG setting. The MX (Mail Exchange) record is a DNS (Domain Name System) record that specifies the mail server responsible for receiving email messages on behalf of a domain. To find the MX record of a domain or SMTP server, you can use various DNS lookup tools or commands, such as `nslookup`, `dig`, or online DNS lookup services.

For example, to check the MX record of a domain using the `nslookup` command in Windows Command Prompt or Linux terminal, you can do the following:

nslookup -type=MX your-target-domain.com

Replace `your-target-domain.com` with the domain you want to check. The output will show you the MX records associated with that domain.

If you do not have a MX record for a mail relay server, you would have to configure the same, respectively contact an administrator who is able to define the same for the network in case. For gmail, for example, you will find some information under Troubleshoot MX records. If, however, you are using gmail as a relay provider, we would highly recommend setting this up using the SMTP server option (please have a look at Can GMail / Google Apps be used for SMTP relay?).

Keep in mind that the MX records can change, and there might be multiple records with different priorities. So, it's always best to perform a fresh DNS lookup to get the most up-to-date information.

I hope you find this information useful to complete your task and if you have any questions please feel free to contact me back.

I tried replying before but I guess it didn't get published. Seems like 1 in 5 of my posts have been published, not sure why.

Thanks for the MX record info, but wouldn't that affect all PRTG emails? Only report emails cause that error. I'm wondering if it is something to do with the attachment. This problem didn't exist before I upgraded to 23.2.84.1566.

The MX record is specific for each target therefore it could work for some and not for others.

There could also be a situation where the access of the DNS server that has the record is not reachable from the PRTG server and because of that, PRTG will not be able to resolve / complete the delivery.

This type of issue is more related to a network issue or a security design due to Firewall configuration setting.