That error message suggests that the SMTP server you are using won't accept email messages with a from: address that is related to some other domain.

Have you set your account to use the emailsrvr smtp server?

I have set my account to use the emailsrvr smtp server

Did you remove the old SMTP server info?

Are you using the secure server, secure.emailsrvr.com on port 465, SSL/TLS? If you're using smtp.emailsrvr.com with no connection security, you might get a 5.7.1 error when sending on a different network.

https://support.rackspace.com/how-to/rackspace-email-and-hosted-exchange-settings/

I removed the old SMTP server info. I changed to secure.emailsrvr.com and still cannot send.

Go to the Help Menu. Click Troubleshooting Information. Then Copy to Clipboard. Come back here and paste that into a reply window.

Application Basics

   Name: Thunderbird
   Version: 52.1.0
   User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0
   Profile Folder: Open Folder

             (Local drive)
   Application Build ID: 20170428151619
   Enabled Plugins: about:plugins
   Build Configuration: about:buildconfig
   Memory Use: about:memory
   Profiles: about:profiles

 Mail and News Accounts
   account1:
     INCOMING: account1, , (none) Local Folders, plain, passwordCleartext

   account2:
     INCOMING: account2, , (pop3) pop.att.yahoo.com:995, SSL, passwordCleartext
     OUTGOING: , smtp.att.yahoo.com:465, SSL, passwordCleartext, true

   account3:
     INCOMING: account3, , (pop3) secure.emailsrvr.com:995, SSL, passwordCleartext
     OUTGOING: , secure.emailsrvr.com:465, SSL, passwordCleartext, true

   account6:
     INCOMING: account6, , (pop3) pop.att.yahoo.com:995, SSL, passwordCleartext
     OUTGOING: , smtp.att.yahoo.com:465, SSL, passwordCleartext, true

   account7:
     INCOMING: account7, , (pop3) pop.att.yahoo.com:995, SSL, passwordCleartext
     OUTGOING: , smtp.att.yahoo.com:465, SSL, passwordCleartext, true

   account8:
     INCOMING: account8, , (pop3) secure.emailsrvr.com:995, SSL, passwordCleartext
     OUTGOING: , secure.emailsrvr.com:465, SSL, passwordCleartext, true

   account11:
     INCOMING: account11, , (pop3) secure.emailsrvr.com:995, SSL, passwordCleartext
     OUTGOING: , secure.emailsrvr.com:465, SSL, passwordCleartext, true

   account12:
     INCOMING: account12, , (imap) imap.gmail.com:993, SSL, OAuth2
     OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true

   account13:
     INCOMING: account13, , (pop3) pop.emailsrvr.com:110, alwaysSTARTTLS, passwordCleartext
     OUTGOING: , secure.emailsrvr.com:465, SSL, passwordCleartext, true

 Crash Reports
   https://crash-stats.mozilla.com/report/index/bp-84fbdc10-36eb-49d4-a02c-208a42161104 (11/3/2016)

 Extensions
   Lightning, 5.4.1, true, {e2fda1a4-762b-4020-b5ad-a41df1933103}

 Important Modified Preferences

   Name: Value

     browser.cache.disk.capacity: 358400
     browser.cache.disk.filesystem_reported: 1
     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
     dom.apps.reset-permissions: true
     extensions.lastAppVersion: 52.1.0
     font.internaluseonly.changed: false
     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: Maiandra GD
     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: 14
     mail.openMessageBehavior.version: 1
     mail.winsearch.firstRunDone: true
     mailnews.database.global.datastore.id: 22a1a6f8-e230-42cb-a3ea-4c21173a72d
     mailnews.database.global.views.conversation.columns: {"threadCol":{"visible":true,"ordinal":"1"},"flaggedCol":{"visible":true,"ordinal":"3"},"attachmentCol":{"visible":false…
     media.gmp.storage.version.observed: 1
     network.cookie.cookieBehavior: 3
     network.cookie.prefsMigrated: true
     network.predictor.cleaned-up: true
     places.database.lastMaintenance: 1493308622
     places.history.expiration.transient_current_max_pages: 122334
     plugin.importedState: true
     plugins.update.notifyUser: true
     print.print_printer: CutePDF Writer

Part 2 of the Troubleshoot Info

print.printer_CutePDF_Writer.print_bgcolor: false

     print.printer_CutePDF_Writer.print_bgimages: false
     print.printer_CutePDF_Writer.print_colorspace:
     print.printer_CutePDF_Writer.print_command:
     print.printer_CutePDF_Writer.print_downloadfonts: false
     print.printer_CutePDF_Writer.print_duplex: 63104
     print.printer_CutePDF_Writer.print_edge_bottom: 0
     print.printer_CutePDF_Writer.print_edge_left: 0
     print.printer_CutePDF_Writer.print_edge_right: 0
     print.printer_CutePDF_Writer.print_edge_top: 0
     print.printer_CutePDF_Writer.print_evenpages: true
     print.printer_CutePDF_Writer.print_footercenter:
     print.printer_CutePDF_Writer.print_footerleft: &PT
     print.printer_CutePDF_Writer.print_footerright: &D
     print.printer_CutePDF_Writer.print_headercenter:
     print.printer_CutePDF_Writer.print_headerleft: &T
     print.printer_CutePDF_Writer.print_headerright: &U
     print.printer_CutePDF_Writer.print_in_color: true
     print.printer_CutePDF_Writer.print_margin_bottom: 0.5
     print.printer_CutePDF_Writer.print_margin_left: 0.5
     print.printer_CutePDF_Writer.print_margin_right: 0.5
     print.printer_CutePDF_Writer.print_margin_top: 0.5
     print.printer_CutePDF_Writer.print_oddpages: true
     print.printer_CutePDF_Writer.print_orientation: 0
     print.printer_CutePDF_Writer.print_page_delay: 50
     print.printer_CutePDF_Writer.print_pagedelay: 500
     print.printer_CutePDF_Writer.print_paper_data: 1
     print.printer_CutePDF_Writer.print_paper_height: 11.00
     print.printer_CutePDF_Writer.print_paper_name:
     print.printer_CutePDF_Writer.print_paper_size_type: 0
     print.printer_CutePDF_Writer.print_paper_size_unit: 0
     print.printer_CutePDF_Writer.print_paper_width: 8.50
     print.printer_CutePDF_Writer.print_plex_name:
     print.printer_CutePDF_Writer.print_resolution: 271104
     print.printer_CutePDF_Writer.print_resolution_name:
     print.printer_CutePDF_Writer.print_reversed: false
     print.printer_CutePDF_Writer.print_scaling: 1.00
     print.printer_CutePDF_Writer.print_shrink_to_fit: false
     print.printer_CutePDF_Writer.print_to_file: false
     print.printer_CutePDF_Writer.print_unwriteable_margin_bottom: 0
     print.printer_CutePDF_Writer.print_unwriteable_margin_left: 0
     print.printer_CutePDF_Writer.print_unwriteable_margin_right: 0
     print.printer_CutePDF_Writer.print_unwriteable_margin_top: 0
     print.printer_Foxit_Reader_PDF_Printer.print_bgcolor: false
     print.printer_Foxit_Reader_PDF_Printer.print_bgimages: false
     print.printer_Foxit_Reader_PDF_Printer.print_duplex: 63104
     print.printer_Foxit_Reader_PDF_Printer.print_edge_bottom: 0
     print.printer_Foxit_Reader_PDF_Printer.print_edge_left: 0
     print.printer_Foxit_Reader_PDF_Printer.print_edge_right: 0
     print.printer_Foxit_Reader_PDF_Printer.print_edge_top: 0
     print.printer_Foxit_Reader_PDF_Printer.print_evenpages: true
     print.printer_Foxit_Reader_PDF_Printer.print_footercenter:
     print.printer_Foxit_Reader_PDF_Printer.print_footerleft: &PT
     print.printer_Foxit_Reader_PDF_Printer.print_footerright: &D
     print.printer_Foxit_Reader_PDF_Printer.print_headercenter:
     print.printer_Foxit_Reader_PDF_Printer.print_headerleft: &T
     print.printer_Foxit_Reader_PDF_Printer.print_headerright: &U
     print.printer_Foxit_Reader_PDF_Printer.print_in_color: true
     print.printer_Foxit_Reader_PDF_Printer.print_margin_bottom: 0.5
     print.printer_Foxit_Reader_PDF_Printer.print_margin_left: 0.5
     print.printer_Foxit_Reader_PDF_Printer.print_margin_right: 0.5
     print.printer_Foxit_Reader_PDF_Printer.print_margin_top: 0.5
     print.printer_Foxit_Reader_PDF_Printer.print_oddpages: true
     print.printer_Foxit_Reader_PDF_Printer.print_orientation: 0
     print.printer_Foxit_Reader_PDF_Printer.print_page_delay: 50
     print.printer_Foxit_Reader_PDF_Printer.print_paper_data: 1
     print.printer_Foxit_Reader_PDF_Printer.print_paper_height: 11.00
     print.printer_Foxit_Reader_PDF_Printer.print_paper_name:
     print.printer_Foxit_Reader_PDF_Printer.print_paper_size_type: 0
     print.printer_Foxit_Reader_PDF_Printer.print_paper_size_unit: 0
     print.printer_Foxit_Reader_PDF_Printer.print_paper_width: 8.50
     print.printer_Foxit_Reader_PDF_Printer.print_resolution: 271104
     print.printer_Foxit_Reader_PDF_Printer.print_reversed: false
     print.printer_Foxit_Reader_PDF_Printer.print_scaling: 1.00
     print.printer_Foxit_Reader_PDF_Printer.print_shrink_to_fit: false
     print.printer_Foxit_Reader_PDF_Printer.print_to_file: false
     print.printer_Foxit_Reader_PDF_Printer.print_unwriteable_margin_bottom: 0
     print.printer_Foxit_Reader_PDF_Printer.print_unwriteable_margin_left: 0
     print.printer_Foxit_Reader_PDF_Printer.print_unwriteable_margin_right: 0
     print.printer_Foxit_Reader_PDF_Printer.print_unwriteable_margin_top: 0
     print.printer_Generic_50C-1_Series_PS.print_bgcolor: false
     print.printer_Generic_50C-1_Series_PS.print_bgimages: false
     print.printer_Generic_50C-1_Series_PS.print_colorspace:
     print.printer_Generic_50C-1_Series_PS.print_command:
     print.printer_Generic_50C-1_Series_PS.print_downloadfonts: false
     print.printer_Generic_50C-1_Seri

Nothing jumps out there. Maybe someone else will see something.

FYI:Next time do not worry about all the printer info. We mainly just want to see server settings.

I do see that you have several addresses on this same server. Do you have an SMTP setting for each one with the corresponding usernames?

Is there an old password blocking access? Tools/Options/Security/Passwords/Saved Passwords, delete any passwords for secure.emailsrvr or smtp.securesrvr, OK, restart TB and enter the correct password when prompted. As mentioned above, you may need to have an outgoing server set up with a user name and password for each emailsrvr account, and then set the Outgoing Server (SMTP) under Tools/Account Settings when you select the account in the left pane.