Do you have any Anti-virus product which is scanning all outgoing mail? If yes, then access Anti-Virus and switch off scanning outgoing mail to see if this improves the performance.

Hi,Toad Hall,I only use Microsoft's Defender as my Antivirus program, I checked it's settings and there was nothing there about scanning my email, I know Thunderbird is the problem, as my wife uses Thunderbird as her Email client as well, same problem, however if I open my email on M/ soft website and send an email with an attachment from there it sends in a flash, going back several month's ago I never had a problem with Thunderbird 'sending' so slow, have tried to find something in settings but no luck, Regards Joe, PS, I use two email addresses, sending from either are the same, My Default address is redacted@hotmail.com

The Microsoft website is a website and has nothing in common with Thunderbird that can be appreciably measure, you would be closer to a comparable product comparing the outlook website with Microsoft.com, and one of those does nothing with emails. The website does all of it's sending in the background, it assumes a mail was sent because you click on the send button. Thunderbird does it all in the foreground offering status updates via the send dialog.

Please define your definition of "slow" in this context. How long between the various messages in the send dialog.

If I send an email using my Hotmail Mail account or GMail account from their website's, the mail goes fast, and I do mean fast, however if I send the same email from my desktop using my thunderbird App it goes very slow compared to website mail, I prefer to use Thunderbird Desktop for my email, both of my email accounts are set up to use Thunderbird, everything works just find but "Sending' is very slow. but never has been in the past.

As I tried to communicate before what happens on the website has no relevance here at all. You are comparing light speed and a bathtub. Silly comparison I agree, but about as close as comparing what happens in Thunderbird with what happens when you click the send button in a webpage.

So again what is "slow"? a minute, 10 minutes, an hour to send from Thunderbird? what constitutes slow. and do not tell me anything about a website you visit. Thunderbird will always and has always has been slower that clicking a a web button because Thunderbird is actually doing thing the web button just implies it has. Google have quite a fast button and a built in delay of actually doing anything at all of one minute to you can click their oops recall button.

Have you tried removing your antivirus email scanning? It also is not involved in the webpage sending. It is a well known show stopper for sending mails however while is scans the email up to 5 times for something it clearly can not detect as it has not already told you that your system is infected.

> Have you tried removing your antivirus email scanning?

The simple test for this is the following...

• Start Windows in safe mode with networking enabled - https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode
• Still In Windows safe mode, start Thunderbird in Troubleshoot Mode - https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird

Does problem change?

If it did not get better, try changing the hidden preference accessibility.force_disabled to 1.

If it did not get better then cause is either: bug in Thunderbird, a setting, file or folder (something) in your Thunderbird profile, your mail provider. Please attach to the bug report or support topic a file created from Help | Troubleshooting | copy text to clipboard

If it did get better , then (still in Windows safe mode) ... start Thunderbird normally -- If problem is still gone, then cause is likely a program loaded during windows startup. Possibilities include: antivirus software (AV), virus/malware, background downloads such as Windows or other program updates, to name a few. For AV information see https://wiki.mozilla.org/Thunderbird:Testing:Antivirus_Related_Performance_Issues -- If problem came back, then cause is likely a Thunderbird add-on - eliminate them by disabling add-ons one at a time in Tools | add-ons | extensions and restart Thunderbird after disabling (if you have many add-ons, try disabling half of them at a time)

- If results are unclear ... possibilities include temporary conditions such as contention from other running programs, downloads related to windows update, ...

Please let us know your findings.

Hi Wayne, I turned off the only anti-virus program I use, which is M/Soft Defender for Windows, its seems to have made sending an email with a 3.1 music track a bit faster, 25 second's ,Thanks for your help, I will be content with that, Regards Joe

Hi Matt, I turned off the only anti-virus program I use, which is M/Soft Defender for Windows, its seems to have made sending an email with a 3.1 music track a bit faster, 25 second's ,Thanks for your help, I will be content with that, Regards Joe

Have you considered you are probably suffering from a slow upload speed. Internet services routinely limit uploads to around 10% of their advertised download speed. It is how they differentiate between their commercial/business class of products (which as usually symmetrical) and residential ones. So you might have a fast download speed, but uploads might be a very different picture.

BTW just how large is the attachment you are sending (they grow about 30% when attached to an email.) You might be better of uploading the file using one of the providers for Thunderbird filelink and only actually sending links to the file in the email rather than the entire file. See https://support.mozilla.org/en-US/kb/filelink-large-attachments