If you send a sample email to me at davidthunderbird at gmx dot com I will look at the issue.

Hi,

I've just sent you sample emails from both email clients. Both emails are sent via the same SMTP gmail account and both have the same signature containing two 18x18 px .gif images.

The one sent via Thunderbird is in gmail's webmail marked with a paperclip while the one sent via Eudora isn't, here is the screenshot.

I compared the raw messages in gmail's Sent mailbox but couldn't figure out what is causing the difference.

Please ask if you need any further data or information. I have one more Thunderbird and Eudora in a virtual machine so I can do tests.

Regards

I found your problem: you're using Comic Sans 😄. (just kidding)

This is a Gmail-side behavior, not necessarily a Thunderbird bug. Gmail can be picky and flag any multipart MIME structure with embedded content as “having attachments”, even if it is technically inline. Eudora uses and older MIME structure and Gmail may be giving them a pass for whatever reason.

Question: Are you attaching an HTML file or pasting your HTML into the block in settings?

He he :-) I have that signature since Geocities times when everything "had" to be excessively decorated :-)) That signature was quite an improvement over ASCII art signatures we were using at university on VAX running Unix. The .gif file was once part of Yahoo! mail's emoticons. Those GIFs are still online but can be accessed only over http.

BTW, I've just searched for "geocities" on Google and all the results have been displayed in Comic Sans :-))

So the difference is in email clients handling MIME. Do you think there is some workaround to prevent all sent emails being marked as "having attachments" in gmail's web interface when I am using Thunderbird? Except using a signature without .gif files, of course :-)

I am attaching an HTML file which I created as descibed in this article about Thunderbird signatures. Do you think pasting the same HTML instead of attaching the file could make a difference?

I have just tried pasting the HTML, checking "Use HTML" and unchecking "Attach the signature from a file" and the result was exactly the same - the mail was marked with the paperclip as before.

I tried adding:

<x-sigsep><p></x-sigsep>

at the beginning of the Thunderbird's signature but the result was:

<div class="moz-signature">-- <br>
      <x-sigsep>
        <p> {HTML of the signature} </p>
      </x-sigsep></div>

and not:

<x-sigsep><p></x-sigsep>
{HTML of the signature}

as when sending with Eudora.

Seems as Thunderbird parses the HTML for the signature and generates a new HTML code based on the original HTML from the signature.

Chupo sent sample email to me and I could detect no problem. see attached. Also, there was no indication of being an attachment.

Chupo sent sample email to me and I could detect no problem. see attached. Also, there was no indication of being an attachment.

Yes, but as I said:

This email message is going to be marked with a paperclip icon in gmail's webmail accessed via browser. It will be marked with paperclip in both Sent mailbox and in the inbox at the recipient's side. It will not be marked with paperclip in Thunderbird which is correct.

Here I attached the screenshot showing the same signature posted with Eudora is not marked with a paperclip in the gmail's webmail - while it is marked with a paperclip in the gmail's webmail when sent by Thunderbird.

So the problem is: "If someone is sending an email using Thunderbird with a signature containing an image via gmail, then every single email they send will on gmail's webmail be marked with a paperclip.".