COMMUNICATION ERROR [334] – but it’s not authentication, maybe throttling?

Dear,
Post SMTP can work with Cloudflare?
I try multi times but no work.
I reset the plugin but no work.
What I need to do to work well or I can not use the SMTP when the site to be over the Cloudflare service?
Thnaks for all help!
S.

@bigredseo are you sending bulk emails?

Can you share your logs here then I will check and get back to you soon?

Thanks

Thanks for the reply. I can’t post the actual logs here as they have email addresses, content and private links in the original_content sections, so is there a better way to get you these logs?

As far as the content being sent, it’s not exactly a bulk email, but they are notices about memberships or subscriptions about to expire. More than 5,000 members in the system and a few hundred get notified on the 1st, with 2-5 notices each other night as their membership dates come up for renewal.

The emails are sent via a cronjob which triggers once each day to see if a user has hit specific metrics (stored in User ACF Fields) and then matches expiration date of subscription. The system then changes their user role if needed.

It acts/looks like a timeout. The “Solution” solucmn says “No found, check status column for more info.”

The status column has the following (domain has been XXXX’d out, as has a portion of the XOAUTH2 string;

"smtp:tls:oauth2://smtp.gmail.com:587

220 smtp.gmail.com ESMTP z4-20020a92d184000000b002b7bdf53db1sm7157949ilz.39 - gsmtp
EHLO XXXXXXXXXXXXXXXXXXXXX.com
250-smtp.gmail.com at your service, [35.209.120.77]
250-SIZE 35882577
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
STARTTLS
220 2.0.0 Ready to start TLS
EHLO XXXXXXXXXXXXXXXXXXXXX.com
250-smtp.gmail.com at your service, [35.209.120.77]
250-SIZE 35882577
250-8BITMIME
250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN OAUTHBEARER XOAUTH
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
AUTH XOAUTH2 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX5lWGt5dDRGWGtzb055cGIzOHZ1eXpZam5OM2ZPZDRqeGVCRlJnVkQ3bzFaa1ZHZXhOOWpVWElWeEgwREFaQTBDeGdnOAEB
334 eyJzdGF0dXMiOiI0MDAiLCJzY2hlbWVzIjoiQmVhcmVyIiwic2NvcGUiOiJodHRwczovL21haWwuZ29vZ2xlLmNvbS8ifQ==
"

Instead of getting a 235 Accepted status and then the mail headers, then the 354 to go ahead with data, it’s returning a 334 status (server challenge) and then dropping off.

Like I said, even though dozens of emails get sent successfully, we then hit this 25 batch, and then no mail between that time and an 90 minutes later. I don’t know if that was the end of the sending, or if other mail just didn’t bother sending since it saw 25 failed attempts.

@bigredseo
thanks for updating us, let me test it and discuss it with my team.

@bigredseo

Can you try this and let us know its working.

`Press “Show all settings”
https://www.awesomescreenshot.com/image/24234753?key=a8f89492717731f892825b02b25fa64d

and change the field to match your account
https://www.awesomescreenshot.com/image/24234755?key=6834af714ba0971c09d7b5b047055366

if after the change you still see the wrong email, another process is changing the email on the fly, so again from settings check these boxes.
https://www.awesomescreenshot.com/image/24234756?key=0236f05e8989e8937a08bd343cd8dc3a

Thanks

Thanks for the reply.

Just to clarify, it’s not a “seeing the wrong email” as a problem. They’re all sending out under an info@ address. The potential theory of mail throttle by gmail.

The “Envelope From Email Address” was filled out. The only thing different on that screen is that you have “Authentication: Plain” and I have “Authentication: oAuth 2.0” which isn’t a problem.

The forcing of the Email Address and Name on the Message Tab I had filled out, but didn’t enforce the Prevention of the change. I have enabled that just for good measure.

Since these are sent directly via a function in a cron script, we’re not defining a FROM either directly or in the $headers. So it should be using the default from the Post SMTP Mailer. Here’s what we were calling;
wp_mail( $to, $subject, $body, $headers );

I didn’t notice any issues on the mail sending for the 16th (we have two BIG days for sending.. 1st & 16th based on the majority of subscriptions ending/renewing).

I extended our logging to 1,000 records so we’ll keep an eye on it and post here during the next big batch.

Thanks again for the reply.

@bigredseo

thanks for updating me, let me know if you again face this issue again on the 1st.