Outgoing emails blocked "550 5.7.1 Reject for policy reason"

[Ellyott]

My outgoing emails are being rejected when they have pdf attachment. 

A plain text email and one with jpg attachment leaves successfully but ones pdf are rejected for policy reasons.  This is true for fresh emails and for replies when sent from outlokk or webmai..

The problem seems to have started since the begning of August.  

[sabelo-TT]

Thank you for the information you have provide @Ellyott. What I have done on my end is to escalate and make this matter a priority to our email team as one of the team members will be in touch with you within 24-72working hours using the contact details available on your account. 

[Ellyott]

Having implemented the auto forward, I've tried resending the two emails.  One has been undelivered againt whilst I have no immediate message on the other one.  

[Ellyott]

Ive done that but I don't understand the logic or auto forwarding my emails from my address to myself at the same address.

[sabelo-TT]

Thank you for this. We need to check to see if there's an email redirection or auto-forward rule in place for your mailbox. Could you be able to check on this for me on your end by simply following steps: 

1. Select Setting cog icon - Once logged in to webmail, the blue task bar going across the screen has 3 horizontal lines on top of each other. Click on this icon

2. Select All Settings - Once selected, it will bring up a list of options. The first option, which is ‘all settings’, is the one we need to select.

3. Select Mail menu - In the left side menu, click the Mail to expand.

4. Scroll Down and Select Rules - Select Rules to expand. Then select the Auto-Forward.

5. Enable and Add email for Auto Forward - Enter the email address that you would like to forward all incoming email messages to this email address. Once done adding it, click Appy Changes if you are okay with the changes.

[Ellyott]

Does that satisfy?

[sabelo-TT]

Basically, I will need for you to update your profile as this will require for you to insert all details which will assist me in locating and verify your account on my end. This will include inserting the full name(s) registered on the account. 

[Ellyott]

Account number added

[sabelo-TT]

Thank you for this. Before continuing any further, please update your community profile and add your landline number and/or account number so your account can be identified. Please don't post personal information here. Please do confirm once done. 

https://community.talktalk.co.uk/t5/user/myprofilepage/tab/personal-profile:personal-info

[Ellyott]

Yes, I have an active TalkTalk account.

Please please please don't repeat all of the conversation of yesterday.  You could read the dialogue with your colleague Kanya-TT below.

[sabelo-TT]

@Ellyott, if I may kindly ask, do you currently have an active broadband account with us (TalkTalk)?

[Ellyott]

I'm now getting a new problem in replying to emails, with no attachments.  Two emails have failed with these messages:

<<< 550-5.7.26 Unauthenticated email from talktalk.net is not accepted due to <<< 550-5.7.26 domain's DMARC policy. Please contact the administrator of <<< 550-5.7.26 talktalk.net domain if this was a legitimate mail. To learn about <<< 550-5.7.26 the DMARC initiative, go to <<< 550 5.7.26  https://support.google.com/mail/?p=DmarcRejection ffacd0b85a97d-3b79c6cc7e8si8204121f8f.759 - gsmtp

554 5.0.0 Service unavailable

host live-com.olc.protection.outlook.com[52.101.9.27]

    said: 550 5.7.515 Access denied, sending domain TALKTALK.NET doesn't meet

    the required authentication level. The sender's domain in the 5322.From

    address doesn't meet the authentication requirements defined for the

    sender. To learn how to fix this see:

    https://go.microsoft.com/fwlink/p/?linkid=2319303 Spf= Pass , Dkim= Fail ,

    DMARC= Pass [DBAP191MB1308.EURP191.PROD.OUTLOOK.COM

    2025-08-06T13:41:30.742Z 08DDD4478593B216]

    [MN0P222CA0025.NAMP222.PROD.OUTLOOK.COM 2025-08-06T13:41:30.777Z

    08DDD4DACD3818DA] [BL02EPF0002992C.namprd02.prod.outlook.com

    2025-08-06T13:41:30.779Z 08DDD03B1A84DBAA] (in reply to end of DATA

    command)

The situation is getting worse than yesterday.  Help.

[Ellyott]

I have access to my emails via Outlook 365 on a laptop, on gmail app in Android and ocasionally using TT webmail via a browser.  I do serious emails with attachments via Outlook on laptop and had tested the issue on both the laptop and TT webmail.

Having tested further it seems that it relates to a pdf edited with Adobe acrobat.  It may be the specific form provided by the bank.  However, the form was received through the virus checkers but TT does not allow it to be sent out.

[sabelo-TT]

@Ellyott, how are you currently accessing your emails? Are you accessing them through the browser via Webmail or accessing through an App?

[Ellyott]

The specific pdf that caused the issue is a bank form that has to be filled in and sent back.  So, its related to a pdf with added text in Adobe Acrobat to a form from the bank.

[Ellyott]

It is not a size problem.  The pdf is only 1.9MB.

The problem seems to be some setting within TalkTalk's "enhanced security" update controlled by TT. 

[Gliwmaeden2]

What is the size of the file, @Ellyott ?

I cannot remember what the limit is with Talktalk, but that can be what stops certain emails sending. 

Staff will be back after 8am.

[Ellyott]

There is a message:

"Changes to your email service

We’ve recently upgraded the TalkTalk Mail service with a new look and enhanced security. Log in below to see what’s changed"

Clearly TalkTalk has made the changes that are causing this issue.

[Ellyott]

There is a mailbox manager but that only has add and add/delete/change password type options

[Ellyott]

I cannot see a "Manage" option or Authentication Settings. The nearest thing is "My Security Settings" which do not have the option for authentication.

Please advise more detailed navigation.

[kanya-TT]

You may need to review your Authentication Settings. 

1. Log in to Your TalkTalk Account

• Go to the TalkTalk website and log in to your account.

2. Access Domain Management

• Navigate to the "Manage" section of your account.

Kanya