I just composed an email in Thunderbird with 8 pg attachments, sent it using gmail to a gmx email address. It tells me on the attachment panel at the bottom I have 8 attachments and 1.3mb of files. When I expand the attachment panel it shows the individual files and sizes as well.

Perhaps you are being sent broken emails. From an Idevice or outlook for example. Both are known to send broken mails on occasion..

Do you have power point installed? It is after all a proprietary file format specific to Microsoft office, although some other office products can open it. (Libre office, open office and some others)

Matt, I can compose & send an email with several attachments to myself or others & the attachments come through as they should - size of total attachments shown & each attachments & size is shown when expanded. The problem which only recently started is with every incoming email from senders I have been receiving from for many years. Power point problem now solved there was an error with media player.

Rob

There is a bug report which sounds like your issue.

• https://bugzilla.mozilla.org/show_bug.cgi?id=1576584

Please try the following:

• Menu app icon > Options > Options > Advanced >'General' tab
• click on 'Config Editor' button
• Accept risk :)
• In search type: mime
• Look for this line: mail.server.default.mime_parts_on_demand
• If it says 'True', then double click on that line to toggle the vlaue to say 'False'
• Close window using top right X.
• Exit Thunderbird and restart Thunderbird.

Please report back on whether new emails with attachments are successful.

Hi Toad-Hall I don't know how to start in your solution. I can follow after the first step, but where do I go to start? Menu app icon??

Thanks Rob

The 'Menu app icon' is located on the 'Mail Toolbar' and it has 3 horizontal lines. By default it is on the far right, but it can be moved, so in example image below, I've moved it to far left.

Hi Toad-Hall

Problem not solved - some attachments OK but just as many still coming in size unknown & each attachment having to be saved as previously outlined before able to send on. In config editor there are five other "mime" lines that say true. Do I need to change any of these to false? Or what do you suggest?

Thanks Rob

Hi again Toad-Hall

I have just realised another issue,which may shed more light on the problem, in emails that the attachments are normal ie the total attachments size is shown & can be forwarded, I can open each separate attachment multiple times, in the ones that do not show the total attachment size, each individual attach can only be opened once each time the email is opened. You can close & reopen the email again & open each separate attachment still only once.

Thanks Rob

Hi Toad-Hall

Anything further you can suggest to rectify the issue I have?

Additionally some emails are coming in with no attachment, but if I forward the email an attachment is included, why is the attachment not displayed when I receive the email? A friend who uses Outlook also has this issue, so is it related to Windows?

Thanks Rob

Do you use the default Windows 10 Anti-Virus or another like Norton or Avast etc?

Do you allow scanning of incoming emails?

Are you currently using Thunderbird version 68.10.0  ?

When you get a size unknown issue, please check on webmail to see what is the actual size of the attachment and what is the extention eg: pdf, jpg etc. It may not necessarilly be a large attachment.

I think you need to actually have a look at the source of the email you are getting with the size unknown attachments

Attachments in an email are not an attachment as you would expect. They are a block on MIME encoded text. This is because of the ancient definitions of email that state only text can be in an email. This definition has been expanded with the use of mime encoding to allow other things to fit into the original specification and still maintain backwards compatibility.

Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="Pay.pdf"
Content-Type: application/pdf; name="Pay.pdf"
Mime-Version: 1.0

The above is an extract from a mime "part" that defines an attachment in a mail from my inbox. Note the Content-Disposition: attachment; This defines the thing as an attachment. If it had been say a JPG it could just as well be defined as inline and Thunderbird would show no attachment clip but would instead have displayed the image (if the HTML referenced it) in the message body. The trouble can come in from the attachment being incorrectly defined by the sender, or it can be that the attachment is actually corrupted.

I have seen over the years many instances where attachments were corrupted by outgoing email scanners to the point that part of the image would display in the case of a jpg, but other important binary data was missing from the end.

It is also possible that the message itself does not end the "mime part" correctly or the attachment is incorrectly defined as something it is not.

If you like, you can forward as an attachment one of the problem email to [email protected] (but if must be the original as an attachment, not a simple forward) and I will have a look at the source and see if I can see something. But no guarantees, I am not an expect, only an amateur :)