Hi, been using Cloudflare free DNS for a long time and never had this issue. I have all DMARC, SPF1, DKIM set up and never had issues with it until this week. Some users started to report not delivered emails, all of them were Gmail users. Looked the server logs and got this:
in.l.google.com[7x.1xx.1x3.2x] said: 550-5.7.26 This message does not have authentication information or fails to 550-5.7.26 pass authentication checks. To best protect our users from spam, the 550-5.7.26 message has been blocked. Please visit 550-5.7.26 https://support.google.com/mail/answer/81126#authentication for more 550 5.7.26 information.
Using SMTP from my hosting company everything runs well but when using phpmailer with cloudflare settings Gmail issues pop up. Only Gmail what makes me believe something is wrong in my cloudflare settings related to some recent gmail update or something. Nothing has been changed, and I’m not sending spam only normal registration emails with links to confirm, also confirmed that I’m not listed in spam lists and MxToolbox tests all say everythings fine. I’m in a dead end