Office 365 Emails Bounce with Bad Outbound Sender, even after Unblocking 7 different days of last 20 days

Question

Office 365 Emails Bounce with Bad Outbound Sender, even after Unblocking 7 different days of last 20 days

Victor Reinhart 11

Hi,

Many of my emails send OK. But on 7 different days out of the last 20 days, I have gotten bouncebacks.

Getting:

Remote Server returned '550 5.1.8 Access denied, bad outbound sender. For more information please go to http://go.microsoft.com/fwlink/?LinkId=526653. S(9333) [BYAPR15MB2392.namprd15.prod.outlook.com]'

We sent no more than 50 emails a day, and no more than 1 email per minute. On 7 different days, I have contacted GoDaddy Support, and have done this:

Changed our email passwords.
Logged off all accounts
Unblocked the email account
Created a TXT record in DNS
Created a SPF record in DNS
Even created a brand-new email account for sending emails.

We can then send email for a few hours. And then the problem comes back within 24 hours.

Each time we unblock the email, the web page shows us the "suspicious" email. This email is not spam, and it's not for marketing either. It is email we send out to our customers. Sometimes we have 2 customers who need the same email. We send it to customer#1, then send a very similar but different email to customer#2 and that shows as "suspicious".

We have a homegrown PHP application we use to send email to our customers and also our "custodians of records". This creates an HTML-format email with a hyperlink. No attachments, no embedded pictures, very simple.

We have fallen a whole week behind in sending emails to our customers and custodians. I have asked to escalate the issue with GoDaddy Support, and they have no answers for me.

It's the same exact issue day after day after day.

The emails are sent just fine. And some of them do get delivered. Then, perhaps an hour later, we get bounceback emails in our inbox, sometimes 20+ emails in a row bounce.

We have been advised many times that a spammer is using our account to send emails. If so, where are they? I have used outlook.com to look at our sent items. There are only items we sent to our customers and custodians. Whenever I unblock, the "suspicious" email is NEVER spam.

My code uses PHPMailer and sends email using SMTP. The support person at GoDaddy suggested this was a bad idea, and I shouldn't use SMTP to send my email. If not, then how should I send it?

Do you have any suggestions?

Sincerely,

Victor Reinhart, on behalf of SierraInfonet.com

KyleXu-MSFT 26,396 Reputation points

2022-06-15T06:03:36.48+00:00

@Victor Reinhart

I would suggest you try the SMTP AUTH client submission

By the way, here are the recommendations for customers who want to send mass mailings through EOP.
Victor Reinhart 11 Reputation points

2022-06-15T15:32:01.39+00:00

Hi,
I appreciate your response. I am no longer using Office 365 to send these emails, and have opened an account with another ISP.

We are not doing bulk emails. We are not doing marketing. Each time the "suspicious" email which was shown to us on the website was an email to our own customer. The customer who hired us to do work for them. The customer who is expecting an email from us.

I used mxtoolbox.com to look up sierrainfonet.com on the blacklists. One - just one - blacklist has us listed. The other 90 blacklists don't have us listed.

It is called RATS Spam. I followed the link to de-list. When I put in the IP address, it says it's not on the list.

This has been the case for the last 20 days. Even though I request to be unblocked from the Office 365 site, I am still listed on SPAM Rats.

It seems to me the problem is not that we are sending bulk mail. Our business practices are the same today as they have been for 25 years. If we were sending bulk email, why have none of the other 90 blacklists ever listed us?

The problem is this one particular blacklist, which has a listing where I can't appeal at all since it says I'm not listed.

Sincerely,
Victor Reinhart