Server Name: old.transpacific.net Port: 587 Connection Settings: STARTTLS Authentication method: Encrypted password

For 'Authentication method' try 'Normal password'.

Did not work.

My ISP sent this to his clients and Mozilla:

I use self-signed certificates, which Thunderbird has never prevented; I use STARTTLS and generally, encrypted passwords. The latest patch causes an error "cannot send for an unknown reason" and that itself is bogus: please have the thing say "because I can't negotiate SSL" or something better than "unknown", the reason is always "known" in the sense of what internal software task step failed.

@CHRIST1 Could it be related to removing support for TLS keys of 512bits?

Quite possible.

jdhallam,

Do you get any error message? Can you also check the Error Console? Tools (Alt-T) - Error Console

Please post a screenshot of any error you may get. http://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

Attempting to send results in the following :

Send Message Error

Sending of the message failed. The message could not be sent using Outgoing server (SMTP) old.transpacific.net for an unknown reason. Please verify that your Outgoing server (SMTP) settings are correct and try again.

In Error Console, there are many posts, the most recent error message is:

Timestamp: 7/19/15 9:12:54 AM Error: An error occurred during a connection to old.transpacific.net:587.

SSL received a weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message.

(Error code: ssl_error_weak_server_ephemeral_dh_key)

I hope that helps.

The error means your email provider's server is not properly configured and exposes you to the LogJam attack. Thunderbird is trying to prevent that. https://weakdh.org/

As a workaround you can install this add-on. https://addons.mozilla.org/en-US/firefox/addon/disable-dhe/

Note, this will allow you to connect to the server in a secure way, but it doesn't address the underlying problem of the server still being vulnerable.

Check this article if you are having difficulties installing the add-on for Thunderbird. http://xenos-email-notes.simplesite.com/416814616

There are many warnings and errors listed in the Error Console, here are some more:

Could not read chrome manifest 'file:///Applications/Thunderbird.app/Contents/Resources/chrome.manifest'.

Could not read chrome manifest 'file:///Applications/Thunderbird.app/Contents/Resources/extensions/%7B972ce4c6-7e08-4474-a285-3208198ce6fd%7D/chrome.manifest'.

Timestamp: 7/19/15 9:06:03 AM Warning: Use of Mutation Events is deprecated. Use MutationObserver instead. Source File: chrome://calendar/content/widgets/calendar-widgets.xml Line: 496

OpenGL compositor Initialized Succesfully. Version: 2.1 ATI-8.12.47 Vendor: ATI Technologies Inc. Renderer: ATI Radeon HD 4670 OpenGL Engine FBO Texture Target: TEXTURE_2D

Timestamp: 7/19/15 9:06:18 AM Warning: This site makes use of a SHA-1 Certificate; it's recommended you use certificates with signature algorithms that use hash functions stronger than SHA-1. Source File: https://www.mozilla.org/en-US/thunderbird/release/start/?uri=/thunderbird/start/&locale=en-US&version=38.1.0&os=Darwin&buildid=20150707103124 Line: 0

Timestamp: 7/19/15 9:06:18 AM Warning: This site makes use of a SHA-1 Certificate; it's recommended you use certificates with signature algorithms that use hash functions stronger than SHA-1. Source File: https://www.mozilla.org/en-US/thunderbird/release/start/?uri=/thunderbird/start/&locale=en-US&version=38.1.0&os=Darwin&buildid=20150707103124 Line: 0

Timestamp: 7/19/15 9:06:18 AM Warning: Unknown property 'padding-start'. Declaration dropped. Source File: https://mozorg.cdn.mozilla.net/media/css/thunderbird-start-bundle.f3f2a61e7492.css

Timestamp: 7/19/15 9:06:18 AM Warning: Unknown property 'margin-start'. Declaration dropped. Source File: https://mozorg.cdn.mozilla.net/media/css/thunderbird-start-bundle.f3f2a61e7492.css

Timestamp: 7/19/15 9:06:21 AM Error: downloadable font: kern: Too large subtable., table discarded (font-family: "Open Sans Light" style:normal weight:normal stretch:normal src index:1) source: https://mozorg.cdn.mozilla.net/media/fonts/OpenSans-Light-webfont.1c8075cacedb.woff Source File: https://mozorg.cdn.mozilla.net/media/css/thunderbird-start-bundle.f3f2a61e7492.css

Timestamp: 7/19/15 9:06:21 AM Error: downloadable font: kern: Too large subtable., table discarded (font-family: "Open Sans" style:normal weight:normal stretch:normal src index:1) source: https://mozorg.cdn.mozilla.net/media/fonts/OpenSans-Regular-webfont.2696e36f12c5.woff Source File: https://mozorg.cdn.mozilla.net/media/css/thunderbird-start-bundle.f3f2a61e7492.css

Timestamp: 7/19/15 9:12:42 AM Error: TypeError: aDocumentNode.cardDetails is undefined Source File: chrome://messenger/content/msgHdrViewOverlay.js Line: 1396

Timestamp: 7/19/15 9:12:42 AM Error: TypeError: aDocumentNode.cardDetails is undefined Source File: chrome://messenger/content/msgHdrViewOverlay.js Line: 1396

Timestamp: 7/19/15 9:12:46 AM Error: DEPRECATION WARNING: Encoding to non-UTF-8 values is obsolete You may find more details about this deprecation at: http://bugzilla.mozilla.org/show_bug.cgi?id=790855 resource://gre/components/mimeJSComponents.js 438 MimeConverter.prototype.encodeMimePartIIStr_UTF8 null 0 null

Source File: resource://gre/modules/Deprecated.jsm Line: 79

Did you try the add-on?

Yes, I tried the patch. I received a message that it was successfully installed, but was not directed to restart T-Bird. I did restart and tried to send a message, but received the same error message.

You should recheck https://support.mozilla.org/en-US/questions/1072871#answer-756134