The usual cause is the sending account is not configured to use a password for the SMTP server.

Please copy into a message here the information on the troubleshooting paging on the help menu.

Copy to clipboard and paste here.

Application Basics

   Name: Thunderbird
   Version: 31.5.0
   User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0
   Profile Folder: Show Folder

             (Local drive)
   Application Build ID: 20150222233048
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory

 Mail and News Accounts
   account1:
     INCOMING: account1, , (pop3) pop.secureserver.net:995, SSL, passwordCleartext
     OUTGOING: smtpout.secureserver.net:465, SSL, passwordCleartext, true

   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

   account4:
     INCOMING: account4, , (pop3) pop.secureserver.net:995, SSL, passwordCleartext
     OUTGOING: smtpout.secureserver.net:465, SSL, passwordCleartext, true

   account7:
     INCOMING: account7, , (pop3) pop.aol.com:995, SSL, passwordCleartext
     OUTGOING: smtp.aol.com:587, alwaysSTARTTLS, passwordCleartext, true

   account8:
     INCOMING: account8, , (rss) Feeds, plain, passwordCleartext

   account10:
     INCOMING: account10, , (pop3) pop.googlemail.com:995, SSL, passwordCleartext
     OUTGOING: smtp.googlemail.com:465, SSL, passwordCleartext, true

   account11:
     INCOMING: account11, , (imap) imap.domainhost.com:143, alwaysSTARTTLS, passwordCleartext
     OUTGOING: smtp.domainhost.com:587, alwaysSTARTTLS, passwordCleartext, true

   account13:
     INCOMING: account13, , (exquilla) mail.numarkassoc.com:443, SSL, passwordCleartext
     OUTGOING: null, plain, passwordCleartext, true

   account14:
     INCOMING: account14, , (imap) imap.readyhosting.com:143, alwaysSTARTTLS, passwordCleartext
     OUTGOING: smtp.readyhosting.com:587, alwaysSTARTTLS, passwordCleartext, true

 Crash Reports
   http://crash-stats.mozilla.com/report/index/bp-20009858-e1d4-4be8-b497-ff8332150219 (2/19/2015)

 Extensions
   ExQuilla for Microsoft Exchange, 31.0.1136, true, [email protected]

 Important Modified Preferences

   Name: Value

     browser.cache.disk.capacity: 358400
     browser.cache.disk.smart_size_cached_value: 358400
     browser.cache.disk.smart_size.first_run: false
     browser.cache.disk.smart_size.use_old_max: false
     extensions.lastAppVersion: 31.5.0
     font.name.monospace.el: Consolas
     font.name.monospace.tr: Consolas
     font.name.monospace.x-baltic: Consolas
     font.name.monospace.x-central-euro: Consolas
     font.name.monospace.x-cyrillic: Consolas
     font.name.monospace.x-unicode: Consolas
     font.name.monospace.x-western: Consolas
     font.name.sans-serif.el: Calibri
     font.name.sans-serif.tr: Calibri
     font.name.sans-serif.x-baltic: Calibri
     font.name.sans-serif.x-central-euro: Calibri
     font.name.sans-serif.x-cyrillic: Calibri
     font.name.sans-serif.x-unicode: Calibri
     font.name.sans-serif.x-western: Calibri
     font.name.serif.el: Cambria
     font.name.serif.tr: Cambria
     font.name.serif.x-baltic: Cambria
     font.name.serif.x-central-euro: Cambria
     font.name.serif.x-cyrillic: Cambria
     font.name.serif.x-unicode: Cambria
     font.name.serif.x-western: Cambria
     font.size.fixed.el: 14
     font.size.fixed.tr: 14
     font.size.fixed.x-baltic: 14
     font.size.fixed.x-central-euro: 14
     font.size.fixed.x-cyrillic: 14
     font.size.fixed.x-unicode: 14
     font.size.fixed.x-western: 14
     font.size.variable.el: 17
     font.size.variable.tr: 17
     font.size.variable.x-baltic: 17
     font.size.variable.x-central-euro: 17
     font.size.variable.x-cyrillic: 17
     font.size.variable.x-unicode: 17
     font.size.variable.x-western: 17
     gfx.direct3d.last_used_feature_level_idx: 0
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: a750fd1e-cd05-42d3-9148-7f0e83ba2b2
     mailnews.database.global.views.conversation.columns: {"threadCol":{"visible":true,"ordinal":"1"},"flaggedCol":{"visible":true,"ordinal":"3"},"attachmentCol":{"visible":false…
     network.automatic-ntlm-auth.trusted-uris: https://mail.numarkassoc.com
     network.cookie.prefsMigrated: true
     places.database.lastMaintenance: 1426266793
     places.history.expiration.transient_current_max_pages: 104858
     plugin.importedState: true
     print.printer_HP_Deskjet_D2600_series.print_reversed: false
     print.printer_HP_Deskjet_D2600_series.print_scaling: 1.00
     print.printer_HP_Deskjet_D2600_series.print_shrink_to_fit: true
     print.printer_HP_Deskjet_D2600_series.print_to_file: false
     print.printer_HP_Deskjet_D2600_series.print_unwriteable_margin_bottom: 0
     print.printer_HP_Deskjet_D2600_series.print_unwriteable_margin_left: 0
     print.printer_HP_Deskjet_D2600_series.print_unwriteable_margin_right: 0
     print.printer_HP_Deskjet_D2600_series.print_unwriteable_margin_top: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_bgcolor: false
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_bgimages: false
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_colorspace:
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_command:
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_downloadfonts: false
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_duplex: 1515870810
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_edge_bottom: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_edge_left: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_edge_right: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_edge_top: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_evenpages: true
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_footercenter:
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_footerleft: &PT
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_footerright: &D
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_headercenter:
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_headerleft: &T
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_headerright: &U
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_in_color: true
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_margin_bottom: 0.5
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_margin_left: 0.5
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_margin_right: 0.5
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_margin_top: 0.5
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_oddpages: true
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_orientation: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_page_delay: 50
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_paper_data: 1
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_paper_height: 11.00
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_paper_name:
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_paper_size_type: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_paper_size_unit: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_paper_width: 8.50
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_plex_name:
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_resolution: 1515870810
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_resolution_name:
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_reversed: false
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_scaling: 1.00
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_shrink_to_fit: true
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_to_file: false
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_unwriteable_margin_bottom: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_unwriteable_margin_left: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_unwriteable_margin_right: 0
     print.printer_HP_Officejet_Pro_8500_A910_(Copy_1).print_unwriteable_margin_top: 0

 Graphics

     Adapter Description: ATI Radeon HD 5450
     Vendor ID: 0x1002
     Device ID: 0x68f9
     Adapter RAM: 1024
     Adapter Drivers: aticfx64 aticfx64 aticfx64 aticfx32 aticfx32 aticfx32 atiumd64 atidxx64 atidxx64 atiumdag atidxx32 atidxx32 atiumdva atiumd6a atitmm64
     Driver Version: 8.773.0.0
     Driver Date: 9-7-2010
     Direct2D Enabled: true
     DirectWrite Enabled: true (6.2.9200.16571)
     ClearType Parameters: ClearType parameters not found
     WebGL Renderer: false
     GPU Accelerated Windows: 1/1 Direct3D 10

     AzureCanvasBackend: direct2d
     AzureSkiaAccelerated: 0
     AzureFallbackCanvasBackend: cairo
     AzureContentBackend: direct2d

 JavaScript

 Incremental GC: 1

 Accessibility

   Activated: 0
   Prevent Accessibility: 0

 Library Versions

     Expected minimum version
     Version in use

     NSPR
     4.10.6
     4.10.6

     NSS
     3.16.2.3 Basic ECC
     3.16.2.3 Basic ECC

     NSS Util
     3.16.2.3
     3.16.2.3

     NSS SSL
     3.16.2.3 Basic ECC
     3.16.2.3 Basic ECC

     NSS S/MIME
     3.16.2.3 Basic ECC
     3.16.2.3 Basic ECC

Thanks for showing this handy "troubleshooting button" in help. Scads of information there!

I'm thinking I want it set now as an IMAP not POP3 style account. Do I need to delete the account and create it again as IMAP?

JimScherrer said

I'm thinking I want it set now as an IMAP not POP3 style account. Do I need to delete the account and create it again as IMAP?

You certainly do. The two protocols are just not compatible. Note that you will manually have to remove the SMTP account. as well as the main account. Tools menu (Alt+T) > account settings and use the account actions button on the selected account in the list. Select outgoing server (SMTP) from the list and delete the appropriate accounts in there.

Which account is causing issues. My guess is secureserver.net, but that may just be my bias against them showing.

Great to hear from you. To remove the POP3 can't I just "Remove" using the app functions for that. (or should it be changed to IMAP in some way I haven't yet figured out). It seems to me that when the account/folder is first set up; you get two choices only, POP3 and IMAP. So, once removed, can't I just set up a new account/folder as IMAP?

Not sure what you mean "Manually remove SMTP"; is that the same as POP3; I need to remove the pop3 account/folder? Or is manually remove smtp referring to something else.

OK, I have "Removed" the POP3 instance of [email protected] email account/folder. Then I recreated the same e-mail address as an IMAP set up. I accepted their port and other defaults (its a ReadyHosting.com, common ISP host). Then I looked down the list of folders and saw one at the very bottom labeled SMTP, and opened it. There were two listings of the secureserver.com and I deleted one; the other was the "Default". There was a blank listing on that list so I deleted that one too. Not sure what I am doing. However, I can send and receive e-mails at this [email protected] e-mail address, which I presume means that it is now IMAP. However, I still get the message that ""The size of the message you are trying to send exceeds a temporary size limit of the server"...

I think the issue is the one you mentioned about SMTP; but not really sure what that means.

Also, I wish I could "change the order" of the e-mail accounts/folders, so that from top to bottom they are in the order of most used. As it is, there is only the "Default" setting, which puts one on top (the Default one). I saw an addon for that feature but was not successful installing it and worried that it was not a good addon.

Are you there? Your help is invaluable. I still can't send a "group mailing" out without getting the message.

Keeps asking me to enter my password for smtp.secureserver.net

https://addons.mozilla.org/thunderbird/addon/manually-sort-folders/

Instructions for install http://chrisramsden.vfast.co.uk/3_How_to_install_Add-ons_in_Thunderbird.html

If you can send a single mail and receive a single mail there is nothing wrong with your setup. If it worked and then stopped, it is most liekly your anti Vitus or it's firewall component. For firewall check full access, auto is a non starter, also check the version apposed. Some ckoke and die on point version increases.

Disable anti virus scanning in your anti virus and reboot your computer, from cold if possible.

Yes, I am able to send a single e-mail. And, sometimes, multiple mails. I'm curious about your suggestion that the source of the problem is the firewall. I have Norton Internet Security. I turned off the firewall, did not reboot, yet it seems to have solved the issue of not causing a message about The size being too large. Is there such a thing as a Thunderbird compliant PC Firewall product (as I need one), if Norton is not acceptable? Also, I still get a message (often) that I need to put in a password for the transmission (is that from the ISP?) or is that from Thunderbird?

I get this message; never got it before and now get it all the time and precludes me sending an e-mail.

"An error occurred while sending mail. The mail server responded: 5.7.1 <[email protected]>: Sender address rejected: not owned by user jsscherrer. Please verify that your email address is correct in your Mail preferences and try again."

Any ideas? Is that coming from some Thunderbird set up, or from my ISP for www.TheCompuseum.org?

The size of the message you are trying to send exceeds a temporary size limit of the server. The message was not sent; try to reduce the message size or wait some time and try again. The server responded: ... temporary failure.