SendinBlue Transactional SMTP Error

I am using SendinBlue as a transactional SMTP provider for my Wordpress site and also for my Cisco VoIP server. We have an older VoIP server and it doesn't support the long passwords Amazon SES requires, or API calls like SendGrid requires.

Lately I've been having an issue where emails sent that contain a E2PDF attachment are missing the entire body of text and the attachment and just a string of text appears like this:

----_SiB-272c5ea1c33f44a8-Part_1--

----_SiB-272c5ea1c33f44a8-Part_1--

I was wondering if anyone had any experience with this.

Hi,

Do you use standard E2Pdf attachment shortcode or setup is different? As we know SendinBlue can also accept URLs.

Do you use any 3rd party email plugins at WordPress? If it's Easy WP SMTP try please to deactivate it or replace with WP Mail SMTP.

You can also check with Empty E2Pdf Template to be sure that it's not connected with PDF size and SendinBlue limits.

We remain at your service.

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We would really appreciate your feedback at WordPress.org!

I use the standard shortcode.

I use the SendinBlue Wordpress Plugin to send email.

Hi,

We tested it on our side and faced same problem. It looks like the problem with SendinBlue plugin directly as we could replicate same issue with just "attachment" added to Formidable Forms mail action. E2Pdf was fully deactivated.

It looks like it was similar issue with Contact Form 7 https://wordpress.org/support/topic/possible-bug-related-to-email-attachments-contact-form-7/

We remain at your service.

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We would really appreciate your feedback at WordPress.org!

Thank you. I've sent this information and all the other information to SendinBlue and they are escalating the issue.