This topic

BT Email refusing to send messages with PDF attachments

Biggles57 — Sun, 15 Mar 2026 18:19:59 GMT

I've recently run into a problem with BT Email refusing to send messages with attachments - typically a PDF file. I've tried both using an email client (Thunderbird) and the webmail service (using Firefox as the browser.) Sometimes I get a failure message claiming that the email falls foul of BT policy on Spam or Phishing - this seems pretty dumb as its just a PDF attachments.

I've seen other posts about the same problem - so this is not a new Issue with the BT Email service.

Any ideas, please? As there's no information in the error message about why the BT Email service considers the message to be Spam or Phishing.

Re: BT Email refusing to send messages with PDF attachments

Leanne_T — Mon, 16 Mar 2026 09:01:04 GMT

Hi there @Biggles57

Thanks for coming to the community.

Do you have your own email address copied in when you get this error message?

Could you try turning your router off and back on to see if the emails send after the reboot?

Thanks 🙂

Leanne.

Re: BT Email refusing to send messages with PDF attachments

Biggles57 — Mon, 16 Mar 2026 09:49:18 GMT

Hi Leanne

I've reset my router. Previously I had copied in my own (talk21) email address and the email arrived there. So the problem seemed to be that the BT Email service was not sending the email to the outside world, nor was it returning an error message when using an email client rather than the web interface (browser.)

I've sent a test message following router reset and that has reached one of my other (outlook) email accounts. I can't test the web service as the BT Email service won't let me log in via my browser (Firefox.) So I don't have any error messages to report at the moment.

Re: BT Email refusing to send messages with PDF attachments

Biggles57 — Mon, 16 Mar 2026 09:53:51 GMT

Reply no. 2

Tried accessing BT Email web using a different browser (Chrome) - logged in successfully there. I often have problems logging into the BT Wholesale portal using Firefox, so there might be a common problem there?

Re: BT Email refusing to send messages with PDF attachments

Leanne_T — Mon, 16 Mar 2026 09:56:17 GMT

Hi @Biggles57

Thanks for coming back to me.

It would be worth trying to clear all cookies and cache for the web browser and trying to log in again. If this continues or you get the same message when sending emails, please get in touch with our email tech guides and they will get this fully investigated for you.

Leanne.

Re: BT Email refusing to send messages with PDF attachments

Biggles57 — Mon, 16 Mar 2026 09:58:48 GMT

Thanks.

Re: BT Email refusing to send messages with PDF attachments

Leanne_T — Mon, 16 Mar 2026 09:59:41 GMT

No problem @Biggles57

Let me know how you get on 🙂

Leanne.

Re: BT Email refusing to send messages with PDF attachments

Biggles57 — Thu, 19 Mar 2026 12:37:29 GMT

Hi Leanne

Sadly, the BT Email service is failing again. Using my Thunderbird email client but over a completely different WAN connection (at my local library) I get the following error message:

Sending of the message failed.
An error occurred while sending mail. The mail server responded: We're sorry, but we can't send your email. Either the subject matter, a link, or an attachment potentially contains
spam, or phishing or malware. Please check or edit your message and try sending it again. (6-1-3-3) ID (6994FCBB02BDF8AB). Please check the message and try again.

Seems to be the same problem - a PDF attachment (which is clean and has been sent to various organisations without issue.)

I can send it fine from one of my outlook accounts, so this appears to be specific to the BT Email service (again.)

Any further ideas? Clearly its not related to my browser nor my router - as I didn't use either when I hit the problem.

Re: BT Email refusing to send messages with PDF attachments

Leanne_T — Thu, 19 Mar 2026 14:16:04 GMT

Hi @Biggles57

Thanks for coming back to me.

I've asked our email support team to take a look into this for you, if they need any extra details I will be in touch.

Leanne.

Re: BT Email refusing to send messages with PDF attachments

Leanne_T — Fri, 20 Mar 2026 08:41:19 GMT

Morning @Biggles57

If this is still the same since you last posted on the community, the team have advised we would need to run some further tests and asked if you can get in touch with our email tech guides.

They will have full access to see what could be causing this and let you know what is needed to get this resolved.

Leanne.