I should note that this is Windows 7 and version 52.6.0

I can't reproduce that.

Do you forward inline or as attachment?

Is the folder containing the original message synchronized?

I can only reproduce it with this particular account - any of the other accounts on the server do not have this problem, nor any of the other clients (about 35) connecting via Thunderbird in our office. Forwarding inline or attachment does not make a difference. The user prefers inline, however.

The folders are not synchronized - global search an indexer is also turned off.

Are your other clients all not synchronised?

I believe that with IMAP you may have just the headers in Thunderbird (especially if not synchronised), and message content will be downloaded on demand. I guess that forwarding such a message gets into trouble because it fails to fetch all the content.

I'd suggest you try copying the message to Local Folders before forwarding it. This should force a download of the complete message. Also check what happens if you do enable synchronisation. And see what the other clients are set for as regards synchronisation.

No other client in our office is set to synchronize any account as we use roaming profiles. No other account on any other machine/client has this issue.

I agree that it seems to be a downloading issue, and you are correct that only the headers are synced. I will try to copy to the local folders and enable synchronization and see what happens and will post a reply.

Thank you!

If you select email to read in Message Pane, I presume the attachment is shown below. Are you able to open that attachment ? After opening and closing attachment, click on 'Forward' button . Is the attachment is now included?

The attachment is shown in the Message Pane, and can be opened, read, and interacted with. When closed, pressing Forward does not include the attachment. Thanks Toad-Hall.

Are you sending emails in plain text or html?

You might read the email as if it is using html but that does not mean it is being sent as html. check:

• 'Menu icon' > 'Options' > 'Options' > 'Composition' > 'General' tab
• click on 'Send Options' button
• select: Send themessages in both Plain Text and HTML'
• click on OK
• click on OK

Then retest forwarding.

Unfortunately, the option noted above was already chosen. Messages are sending in plain text and HTML. I had the user uncheck 'Send messages as plain text if possible' and re-test, and they still could not forward with attachments intact.

I will have them attempt to copy it to local folders and then forward from there (they were out of the office on Friday).

Thank you!

Regarding the original sender of email, do you know if they use outlook?

• https://support.mozilla.org/en-US/questions/1061284

Chosen solution This is common with mail generated in Microsoft Outlook. Outlook does not encode attachments correctly so they don't forward. Use 'forward as attachment' for the mail instead of forward to include the attachments.

• Right click on email in list > 'Forward As' > 'Attachment'

Copying the message to the Local Folders and then trying to forward (from the Local Folders) still drops the attachment once the forward compose window opens.

Regarding Outlook vs. other clients - I'm not certain.

I have had the user try to forward as attachment and it did not work, but will try again.

The user just let me know that it is only Acrobat files (.PDF) that seem to be having trouble. They mentioned that they were able to forward a .docx earlier today without issue.

Should I clear file associations in Thunderbird?

This tells Thunderbird which program will be used to open a .pdf document.

• Menu icon > Options > Options > Attachments > 'Incoming' tab

Content type: 'Adobe Acrobat Document' (application/pdf: .pdf )

• Action : Choose ' Use Adobe Reader (default)'
• click on 'OK'

See image below

Q: What is in the source code of received email with pdf attachment?

• select email so it shows in Message Pane.
• click on 'More' and select 'View source'

The following is an example of the info I'm looking for. Look through the source code starting at the top and copy paste each section into this forum question, anything that looks like the following:

MIME-Version: 1.0 Content-Type: multipart/mixed;

boundary="------------B80BFAC86E079BE45BC21B94"

Content-Language: en-GB

This is a multi-part message in MIME format.

Content-Type: multipart/alternative;

boundary="------------3697644408C1BB51B87B0A35"

Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit

Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: 7bit

Content-Type: application/pdf;

name="TEST.pdf"

Content-Transfer-Encoding: base64 Content-Disposition: attachment;

filename="TEST.pdf"

Q: What Anti-Virus product do you use to scan incoming emails?

Please confirm opening the pdf to read uses Adobe Reader and is ok. This would mean the Options > Attachments info is also OK.

I did ask: Q: What Anti-Virus product do you use to scan incoming emails? But I do mean incoming and outgoing? Please confirm if that particular email with pdf can send using the 'Forward as attachment' method?

Opening the PDF to read uses Acrobat Standard and is fine.

Options->Attachments also ok.

Anti-Virus - unless Microsoft Security Essentials does an on-demand scan of TB email store, none.

On server-side, clamav.

Forward as attachment -does- work for the PDF in question. So this is a known problem with Outlook message formatting?

re :Forward as attachment -does- work for the PDF in question. that is good, at least you know this method does work.

re :So this is a known problem with Outlook message formatting? Outlook has had issues over the years with attachments. But this is a link to the most recent one which I've discovered: http://www.mgdking.com/post/outlook-2016-cannot-forward-attachments-kb4011626-issue