Title: Problematic headers Last modified: March 8, 2023 --- # Problematic headers * Resolved [Gerard Blanco](https://wordpress.org/support/users/sixaxis/) * (@sixaxis) * [3 years, 1 month ago](https://wordpress.org/support/topic/problematic-headers/) * Hi Jeff, * I’m here breaking my head over this issue. I have only very basic PHP knowledge so maybe you know better where to look. * Environment: - Default CFX settings - Using SMTP through SMTP Mailer plugin * I’ve found out that the mail is sent only if I comment the line 108 in core-email. php or if change such header to anything else. For example, `Whatever: whatever`. * If the line stays as it is, I get an error: [https://i.imgur.com/YUCLYvD.png](https://i.imgur.com/YUCLYvD.png) * Any clue? Viewing 10 replies - 1 through 10 (of 10 total) * Thread Starter [Gerard Blanco](https://wordpress.org/support/users/sixaxis/) * (@sixaxis) * [3 years, 1 month ago](https://wordpress.org/support/topic/problematic-headers/#post-16540563) * FYI, this is the line: [https://i.imgur.com/0tOziRY.png](https://i.imgur.com/0tOziRY.png) * Plugin Author [Jeff Starr](https://wordpress.org/support/users/specialk/) * (@specialk) * [3 years, 1 month ago](https://wordpress.org/support/topic/problematic-headers/#post-16541081) * Glad to help. I don’t use SMTP for anything so not sure what might be happening or needs done, etc. I am glad to help though if there is any way possible, let me know what I can do. * Thread Starter [Gerard Blanco](https://wordpress.org/support/users/sixaxis/) * (@sixaxis) * [3 years, 1 month ago](https://wordpress.org/support/topic/problematic-headers/#post-16542409) * Thank you, Jeff. I would appreciate any tip about how to troubleshoot this, because I’m basically stuck. Commenting the line makes the form work. Uncommenting it makes the form stop working. * And it doesn’t matter if I change the `$headers` variable to be an array either. For some reason, the `From:` header breaks the form 🙁 * Thread Starter [Gerard Blanco](https://wordpress.org/support/users/sixaxis/) * (@sixaxis) * [3 years, 1 month ago](https://wordpress.org/support/topic/problematic-headers/#post-16544068) * Hey Jeff, * Solved it. In the end the problem was in the SMTP plugin. I just had to change it and that’s it. * Sorry for the false alarm! * Plugin Author [Jeff Starr](https://wordpress.org/support/users/specialk/) * (@specialk) * [3 years, 1 month ago](https://wordpress.org/support/topic/problematic-headers/#post-16544875) * No problem, glad you got it sorted [@sixaxis](https://wordpress.org/support/users/sixaxis/). * Thread Starter [Gerard Blanco](https://wordpress.org/support/users/sixaxis/) * (@sixaxis) * [3 years, 1 month ago](https://wordpress.org/support/topic/problematic-headers/#post-16547099) * Just a little update for those who have the same problem. A solution was to switch SMTP plugins, like I mentioned. * But I also found out that if you still want Contact Form X and SMTP Mailer to work together, you must have the **exact **same address you set up in SMTP Mailer as From address in Contact Form X. * Plugin Author [Jeff Starr](https://wordpress.org/support/users/specialk/) * (@specialk) * [3 years, 1 month ago](https://wordpress.org/support/topic/problematic-headers/#post-16548448) * Good to know, thank you for reporting [@sixaxis](https://wordpress.org/support/users/sixaxis/). * Also other than SMTP Mailer, which SMTP plugin works with CFX? - This reply was modified 3 years, 1 month ago by [Jeff Starr](https://wordpress.org/support/users/specialk/). * Thread Starter [Gerard Blanco](https://wordpress.org/support/users/sixaxis/) * (@sixaxis) * [3 years ago](https://wordpress.org/support/topic/problematic-headers/#post-16551168) * I’ve tried Easy WP SMTP and SMTP Mailer. Easy WP SMTP works out of the box with any sender address you input, and SMTP Mailer requires that you send it from the same one you configure in there. At least, that’s what my tests show. FYI, this is what the author of SMPT Mailer has to say: [https://wordpress.org/support/topic/not-working-with-contact-form-x/](https://wordpress.org/support/topic/not-working-with-contact-form-x/) * Plugin Author [Jeff Starr](https://wordpress.org/support/users/specialk/) * (@specialk) * [3 years ago](https://wordpress.org/support/topic/problematic-headers/#post-16552191) * Thanks, so would this sound accurate: - CFX is compatible with Easy WP SMTP out of the box - CFX is compatible with SMTP Mailer when the setting “Email Address From” is the same as the email set up in SMTP Mailer * That way I can add to the readme/docs FAQs. * Thread Starter [Gerard Blanco](https://wordpress.org/support/users/sixaxis/) * (@sixaxis) * [3 years ago](https://wordpress.org/support/topic/problematic-headers/#post-16552939) * Yes, Jeff, that sounds good 🙂 Viewing 10 replies - 1 through 10 (of 10 total) The topic ‘Problematic headers’ is closed to new replies. * ![](https://ps.w.org/contact-form-x/assets/icon-256x256.jpg?rev=1889318) * [Contact Form X](https://wordpress.org/plugins/contact-form-x/) * [Frequently Asked Questions](https://wordpress.org/plugins/contact-form-x/#faq) * [Support Threads](https://wordpress.org/support/plugin/contact-form-x/) * [Active Topics](https://wordpress.org/support/plugin/contact-form-x/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/contact-form-x/unresolved/) * [Reviews](https://wordpress.org/support/plugin/contact-form-x/reviews/) * 10 replies * 2 participants * Last reply from: [Gerard Blanco](https://wordpress.org/support/users/sixaxis/) * Last activity: [3 years ago](https://wordpress.org/support/topic/problematic-headers/#post-16552939) * Status: resolved