Mail with Reply-To header not delivered

Hey!

Last night I debugged a client website and found out that, emails that contain a “Reply-To” header don’t get delivered by Brevo.

The client website has a contact form that is setup to send E-Mails containing the message creators email address as a reply-to email on submit. This way the client receiving the message can comfortable reply with one click inside the email client.

If I deactivate the transactional email of the brevo plugin the email is delivered.
Also with the transactional email of the brevo activated I can see the email being send inside a SMTP logging plugin. The brevo log of the client don’t show the email. Therefore I guess the email is lost somewhere inside the sending service.

Is the behavior intended?

Greetings
derRALF