User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/113.0

Steps to reproduce:

the problem I have in Thunderbird is that when I attach a file with a long name, it is sent without giving an error, but it never arrives.
For example, if the name of the attachment is "2.4.6 Protocol for&_ Health Emergency COVID19 JM + Rev06.png" it does not arrive and thunderbird does not indicate a sending error.
But if the name of the attachment is "2.4.6 Emergency&_Protocol.png" it reaches its destination without problems.
I change the option
"mail.strictly_mime.parm_folding" but doesnt work

Exsamples:
File Name: "214161Protocol1for1Health1Emergency1COVID191JM1Rev061111.jpg" arrives without problems
File Name: "2.4.6 Protocol for&_ Health Emergency COVID19 JM Rev06.png" Does not arrive
File Name: "246 Protocol for1Health Emergency_ + COVID191JM1Rev061111.jpg" Does not arrive
File Name: "2.4.6 Protocol for1Health.jpg" arrives without problems

This problem started from version 80 of Thunderbird.
I currently have version 112 and the problem continues.
Thank you

Actual results:

The E-mail never arrive to the destination.

Expected results:

The e-mail attach arrived without problems whatever the file name was.

Works for me on Daily 115.0a1 (2023-05-17) (64-bit), Win10.

All attachments with the respective names arrived correctly. Sent by gmail-IMAP, received by gmx-IMAP.

(In reply to Pablo Vitalone from comment #0)

I change the option
"mail.strictly_mime.parm_folding" but doesnt work

• Can you please clarify: What was the value for that pref when the bug occurred?

I currently have version 112 and the problem continues.

• Can you please update to the latest Beta, 114.0b3 (64-bit), and check if the bug still occurs there?
• Does the bug still happen with ≡ > Help > Troubleshoot Mode…?
• Do you have any encryption or signature applied to outgoing affected messages?

The E-mail never arrive to the destination.

• How did you verify that it didn't arrive at destination? Also checked spam folders?
• Can you please check the copy of the message in your own Sent folder - does that have the correct attachments for the problematic attachment names?

(In reply to Thomas D. (:thomas8) from comment #2)

(In reply to Pablo Vitalone from comment #0)

I change the option
"mail.strictly_mime.parm_folding" but doesnt work

• Can you please clarify: What was the value for that pref when the bug occurred?

I currently have version 112 and the problem continues.

• Can you please update to the latest Beta, 114.0b3 (64-bit), and check if the bug still occurs there?
• Does the bug still happen with ≡ > Help > Troubleshoot Mode…?
• Do you have any encryption or signature applied to outgoing affected messages?

The E-mail never arrive to the destination.

• How did you verify that it didn't arrive at destination? Also checked spam folders?
• Can you please check the copy of the message in your own Sent folder - does that have the correct attachments for the problematic attachment names?

Hi Thomas,

I change the option

"mail.strictly_mime.parm_folding" but doesnt work.
I test with 0 and 1 Value. Same resaults

• Can you please update to the latest Beta, 114.0b3 (64-bit), and check if the bug still occurs there?
  The problem continue. I dont know why with version 78 and previus, same profile same accounts works.

• Does the bug still happen with ≡ > Help > Troubleshoot Mode…?
  Already test, same resaults.

• Do you have any encryption or signature applied to outgoing affected messages?
  configuration without any encryptation.

I Make another test, same account in Microsoft outlook, same SMTP server, same E-mail with attach and works.

Thanks