ZeroSMTPFree SMTP relay for printers, scanners and legacy apps that cannot do OAuth 2.0. Plain username/password auth, 200 messages a day from an @msgwing.com address.2026-08-24T21:26:20+00:00https://docs.msgwing.com/ZeroSMTPToshiba: printers and MFPshttps://docs.msgwing.com/devices/toshiba-printers-and-mfps.html2026-08-24T21:24:46+00:00Toshiba printers and MFPs and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.Synology: NAS notification emailhttps://docs.msgwing.com/devices/synology-nas-notification-email.html2026-08-24T21:24:46+00:00Synology NAS notification email and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.Sharp: printers and MFPshttps://docs.msgwing.com/devices/sharp-printers-and-mfps.html2026-08-24T21:24:46+00:00Sharp printers and MFPs and the Microsoft 365 SMTP AUTH shutdown: some models or versions, with a link to the vendor's own statement and what to do if firmware is not an option.Lexmark: printers and MFPshttps://docs.msgwing.com/devices/lexmark-printers-and-mfps.html2026-08-24T21:24:46+00:00Lexmark printers and MFPs and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.HP: printers and MFPshttps://docs.msgwing.com/devices/hp-printers-and-mfps.html2026-08-24T21:24:46+00:00HP printers and MFPs and the Microsoft 365 SMTP AUTH shutdown: some models or versions, with a link to the vendor's own statement and what to do if firmware is not an option.SMTP send-email code examples, 19 languageshttps://docs.msgwing.com/CODE-EXAMPLES.html2026-08-24T21:24:46+00:00Ready-to-run SMTP send-email examples for mx.msgwing.com in Python, PHP, Node.js, TypeScript, Java, C#, C, Go, Ruby, Perl, Rust, Kotlin, Dart, Zig, Elixir, Lua, Swift, PowerShell and Bash, plus Ansible and Docker Compose recipes.Free SMTP relay that still accepts basic authhttps://docs.msgwing.com/2026-08-23T12:00:07+00:00Free SMTP relay for printers, scanners and legacy apps hit by the Microsoft 365 SMTP AUTH shutdown. 200 messages a day from a generated @msgwing.com address.Windows Server SMTP: IIS, PowerShell, Exchangehttps://docs.msgwing.com/WINDOWS-SERVER.html2026-08-23T16:20:34+00:00Send email from Windows Server without a local relay: ASP.NET web.config, PHP on IIS, scheduled PowerShell tasks, and Exchange send connectors.SMTP troubleshooting: ports, TLS, auth errorshttps://docs.msgwing.com/TROUBLESHOOTING.html2026-08-23T12:00:07+00:00Why SMTP sending hangs or fails: cloud providers blocking outbound ports, certificate verification problems, authentication errors and rate limits.Linux system-wide mail relay: Postfix, msmtphttps://docs.msgwing.com/SYSTEM-MTA.html2026-08-23T16:20:34+00:00Route all system mail (cron, monitoring, unattended-upgrades) through an SMTP relay, with systemd failure alerts and an Ansible rollout playbook.Scan to email from a home printerhttps://docs.msgwing.com/SCAN-TO-EMAIL-HOME.html2026-08-23T11:07:36+00:00What an SMTP server is, why Gmail and Hotmail stopped working with printers, and how to get scan-to-email working again for free.Printer scan-to-email SMTP setup by brandhttps://docs.msgwing.com/PRINTERS.html2026-08-23T11:07:36+00:00Fix scan-to-email after Microsoft 365 disables Basic auth. Per-brand SMTP settings for Ricoh, Canon, Xerox, HP, Kyocera, Konica Minolta, Sharp and more.Printer cannot verify the mail server certificatehttps://docs.msgwing.com/PRINTER-CERTIFICATE-ERROR.html2026-08-23T12:00:07+00:00Why an older printer rejects a valid Let's Encrypt certificate, and the one case where turning verification off is the right answer.Monitoring alerts via SMTP relayhttps://docs.msgwing.com/MONITORING.html2026-08-23T16:20:34+00:00Drop-in email alert configuration for Zabbix, Nagios/Icinga, Uptime Kuma and PRTG using a free SMTP relay.Linux SMTP setup: Debian, Ubuntu, Fedora+https://docs.msgwing.com/LINUX.html2026-08-23T16:20:34+00:00Per-distribution package names and setup for sending email from Linux scripts and applications.IIS SMTP relay and Microsoft 365https://docs.msgwing.com/IIS-SMTP-RELAY.html2026-08-23T10:50:54+00:00The IIS SMTP Server feature relaying to Microsoft 365: what breaks when Basic auth ends in December 2026, and what to do about it.HP printer: SMTP server requires authenticationhttps://docs.msgwing.com/HP-PRINTER-SMTP.html2026-08-23T10:56:07+00:00What an HP printer means by SMTP server requires authentication, and what changes when Microsoft 365 drops Basic auth in December 2026.535 5.7.139 and other SMTP AUTH errorshttps://docs.msgwing.com/ERROR-MESSAGES.html2026-08-23T10:18:44+00:00What 535 5.7.139, SmtpClientAuthentication is disabled for the Tenant or Mailbox, 535 5.7.3 and Kyocera send error 1102 actually mean, the four different causes behind them, and which are still reversible.OAuth compatibility by device and producthttps://docs.msgwing.com/DEVICE-COMPATIBILITY.html2026-08-23T12:25:08+00:00Which printers, MFPs, NAS units and applications have an OAuth 2.0 path for the Microsoft 365 SMTP AUTH shutdown and which the vendor has ruled out, with a link to every vendor statement.Canon Maxify MB2755 and other device fixeshttps://docs.msgwing.com/DEVICE-CASE-STUDIES.html2026-08-23T12:00:07+00:00Confirmed, hardware-tested SMTP fixes for specific printer and MFP models, including the Canon Maxify MB2755 certificate-verification issue: quirks and firmware limits the manuals don't mention.SMTP settings for popular applicationshttps://docs.msgwing.com/APPS.html2026-08-23T16:20:34+00:00Ready-to-use SMTP configuration for common applications and platforms.ZeroSMTP vs. other free SMTP relayshttps://docs.msgwing.com/ALTERNATIVES.html2026-08-23T12:10:44+00:00How ZeroSMTP compares to SMTP2GO, Brevo and MailerSend: no DNS setup vs. sending from your own verified domain.535 5.7.3 Authentication unsuccessfulhttps://docs.msgwing.com/errors/535-5-7-3-authentication-unsuccessful.html2026-08-23T16:18:07+00:00What 535 5.7.3 Authentication unsuccessful means, whether it can still be turned back on, and what to do if it cannot.535 5.7.139 SmtpClientAuthentication is disabledhttps://docs.msgwing.com/errors/535-5-7-139-smtpclientauthentication-is-disabled-for-the-tenant.html2026-08-23T16:18:07+00:00What 535 5.7.139 SmtpClientAuthentication is disabled for the Tenant means, whether it can still be turned back on, and what to do if it cannot.535 5.7.139 SmtpClientAuthentication is disabledhttps://docs.msgwing.com/errors/535-5-7-139-smtpclientauthentication-is-disabled-for-the-mailbox.html2026-08-23T16:18:07+00:00What 535 5.7.139 SmtpClientAuthentication is disabled for the Mailbox means, whether it can still be turned back on, and what to do if it cannot.535 5.7.139 Authentication unsuccessful, basichttps://docs.msgwing.com/errors/535-5-7-139-basic-authentication-is-disabled.html2026-08-23T16:18:07+00:00What 535 5.7.139 Authentication unsuccessful, basic authentication is disabled means, whether it can still be turned back on, and what to do if it cannot.5.7.236 Tenant has exceeded its daily limit forhttps://docs.msgwing.com/errors/5-7-236-tenant-daily-limit-per-recipient.html2026-08-23T09:53:48+00:00What 5.7.236 Tenant has exceeded its daily limit for sending email means, whether it can still be turned back on, and what to do if it cannot.5.7.233 Tenant exceeded its daily limit forhttps://docs.msgwing.com/errors/5-7-233-tenant-daily-limit-external-recipients.html2026-08-23T09:53:48+00:00What 5.7.233 Tenant exceeded its daily limit for sending email to external recipients means, whether it can still be turned back on, and what to do if it cannot.5.7.232 Trial tenant has exceeded its dailyhttps://docs.msgwing.com/errors/5-7-232-trial-tenant-daily-sending-limit.html2026-08-23T09:53:48+00:00What 5.7.232 Trial tenant has exceeded its daily limit for sending email means, whether it can still be turned back on, and what to do if it cannot.How much public code breaks in December 2026https://docs.msgwing.com/BLAST-RADIUS.html2026-08-22T16:56:25+00:00A weekly count of public files on GitHub that still point at Microsoft 365 SMTP, and what the number does and does not mean.550 5.7.60 SMTP; Client does not havehttps://docs.msgwing.com/errors/550-5-7-60-client-does-not-have-permissions-to-send-as-this-sender.html2026-08-22T18:19:39+00:00What 550 5.7.60 SMTP; Client does not have permissions to send as this sender means, whether it can still be turned back on, and what to do if it cannot.535 5.7.57 SMTP; Client was not authenticated tohttps://docs.msgwing.com/errors/535-5-7-57-client-was-not-authenticated-to-send-anonymous-mail.html2026-08-22T18:19:39+00:00What 535 5.7.57 SMTP; Client was not authenticated to send anonymous mail means, whether it can still be turned back on, and what to do if it cannot.530 5.7.1 Delivery not authorizedhttps://docs.msgwing.com/errors/530-5-7-1-delivery-not-authorized.html2026-08-22T18:19:39+00:00What 530 5.7.1 Delivery not authorized means, whether it can still be turned back on, and what to do if it cannot.5.7.64 TenantAttribution; Relay Access Deniedhttps://docs.msgwing.com/errors/5-7-64-tenantattribution-relay-access-denied.html2026-08-22T18:19:39+00:00What 5.7.64 TenantAttribution; Relay Access Denied means, whether it can still be turned back on, and what to do if it cannot.5.7.367 Remote server returned not permitted tohttps://docs.msgwing.com/errors/5-7-367-remote-server-returned-not-permitted-to-relay.html2026-08-22T18:19:39+00:00What 5.7.367 Remote server returned not permitted to relay means, whether it can still be turned back on, and what to do if it cannot.5.7.136 Sender was not authenticatedhttps://docs.msgwing.com/errors/5-7-136-sender-was-not-authenticated.html2026-08-22T18:19:39+00:00What 5.7.136 Sender was not authenticated means, whether it can still be turned back on, and what to do if it cannot.5.7.134 Sender was not authenticated for mailboxhttps://docs.msgwing.com/errors/5-7-134-sender-was-not-authenticated-for-mailbox.html2026-08-22T18:19:39+00:00What 5.7.134 Sender was not authenticated for mailbox means, whether it can still be turned back on, and what to do if it cannot.5.7.133 Sender not authenticated for grouphttps://docs.msgwing.com/errors/5-7-133-sender-not-authenticated-for-group.html2026-08-22T18:19:39+00:00What 5.7.133 Sender not authenticated for group means, whether it can still be turned back on, and what to do if it cannot.5.7.12 Sender was not authenticated byhttps://docs.msgwing.com/errors/5-7-12-sender-was-not-authenticated-by-organization.html2026-08-22T18:19:39+00:00What 5.7.12 Sender was not authenticated by organization means, whether it can still be turned back on, and what to do if it cannot.5.4.1 Relay Access Deniedhttps://docs.msgwing.com/errors/5-4-1-relay-access-denied.html2026-08-22T18:19:39+00:00What 5.4.1 Relay Access Denied means, whether it can still be turned back on, and what to do if it cannot.Xerox: ConnectKey printers and MFPshttps://docs.msgwing.com/devices/xerox-connectkey-printers-and-mfps.html2026-08-16T17:58:52+00:00Xerox ConnectKey printers and MFPs and the Microsoft 365 SMTP AUTH shutdown: some models or versions, with a link to the vendor's own statement and what to do if firmware is not an option.Veeam: Backup for Microsoft 365 and relatedhttps://docs.msgwing.com/devices/veeam-backup-for-microsoft-365-and-related-products.html2026-08-16T17:58:52+00:00Veeam Backup for Microsoft 365 and related products and the Microsoft 365 SMTP AUTH shutdown: some models or versions, with a link to the vendor's own statement and what to do if firmware is not an option.Ricoh: multifunction printershttps://docs.msgwing.com/devices/ricoh-multifunction-printers.html2026-08-16T17:58:52+00:00Ricoh multifunction printers and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.QNAP: NAS notification settingshttps://docs.msgwing.com/devices/qnap-nas-notification-settings.html2026-08-16T17:58:52+00:00QNAP NAS notification settings and the Microsoft 365 SMTP AUTH shutdown: no oauth for this purpose, with a link to the vendor's own statement and what to do if firmware is not an option.Microsoft: Teams Roomshttps://docs.msgwing.com/devices/microsoft-teams-rooms.html2026-08-16T17:36:45+00:00Microsoft Teams Rooms and the Microsoft 365 SMTP AUTH shutdown: oauth available, with a link to the vendor's own statement and what to do if firmware is not an option.Microsoft: Dynamics NAV / Business Centralhttps://docs.msgwing.com/devices/microsoft-dynamics-nav-business-central.html2026-08-16T17:58:52+00:00Microsoft Dynamics NAV / Business Central and the Microsoft 365 SMTP AUTH shutdown: some models or versions, with a link to the vendor's own statement and what to do if firmware is not an option.ManageEngine: OpManagerhttps://docs.msgwing.com/devices/manageengine-opmanager.html2026-08-16T17:58:52+00:00ManageEngine OpManager and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.Laserfiche: Workflow emailhttps://docs.msgwing.com/devices/laserfiche-workflow-email.html2026-08-16T17:58:52+00:00Laserfiche Workflow email and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.Kyocera: MFPs reporting send error 1102https://docs.msgwing.com/devices/kyocera-mfps-reporting-send-error-1102.html2026-08-16T17:58:52+00:00Kyocera MFPs reporting send error 1102 and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.Konica Minolta / DEVELOP: ineo and ineo+ MFPshttps://docs.msgwing.com/devices/konica-minolta-develop-ineo-and-ineo-mfps.html2026-08-16T17:58:52+00:00Konica Minolta / DEVELOP ineo and ineo+ MFPs and the Microsoft 365 SMTP AUTH shutdown: no oauth firmware planned, with a link to the vendor's own statement and what to do if firmware is not an option.Faxination: fax serverhttps://docs.msgwing.com/devices/faxination-fax-server.html2026-08-16T17:58:52+00:00Faxination fax server and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.Cisco: Unity Connectionhttps://docs.msgwing.com/devices/cisco-unity-connection.html2026-08-16T17:58:52+00:00Cisco Unity Connection and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.Cerberus: FTP Serverhttps://docs.msgwing.com/devices/cerberus-ftp-server.html2026-08-16T17:58:52+00:00Cerberus FTP Server and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.Canon: Maxify MB2755https://docs.msgwing.com/devices/canon-maxify-mb2755.html2026-08-16T17:58:52+00:00Canon Maxify MB2755 and the Microsoft 365 SMTP AUTH shutdown: no oauth for this purpose, with a link to the vendor's own statement and what to do if firmware is not an option.Brother: printers, MFPs and document scannershttps://docs.msgwing.com/devices/brother-printers-mfps-and-document-scanners.html2026-08-16T17:58:52+00:00Brother printers, MFPs and document scanners and the Microsoft 365 SMTP AUTH shutdown: check vendor advisory, with a link to the vendor's own statement and what to do if firmware is not an option.Printers that will never get OAuth firmwarehttps://docs.msgwing.com/NO-OAUTH-FIRMWARE.html2026-08-11T19:49:05+00:00Printer and MFP models whose vendor has confirmed no OAuth 2.0 firmware is planned for the Microsoft 365 SMTP AUTH shutdown, including the Konica Minolta ineo models marked N/A, and what is actually left once firmware is ruled out.Exchange Online SMTP AUTH Basic auth shutdownhttps://docs.msgwing.com/EXCHANGE-ONLINE-SMTP-AUTH.html2026-08-11T20:32:56+00:00Microsoft disables Basic auth for SMTP AUTH at the end of 2026. Timeline, the 535 5.7.139 error, and every migration option for printers and legacy apps.Systems affected by the SMTP AUTH shutdownhttps://docs.msgwing.com/AFFECTED-SYSTEMS.html2026-08-11T19:30:27+00:00Risk assessment of printers, NAS units, backup jobs, monitoring tools and line-of-business apps that stop sending email, with a PowerShell audit.FAQ — custom domains, usernames, limitshttps://docs.msgwing.com/FAQ.html2026-08-04T18:44:53+00:00Can I use ZeroSMTP with my own hosting and domain? Will mail come from my domain? Sending limits, custom usernames, and why it is free.Reliable email sending: retries and backoffhttps://docs.msgwing.com/RELIABILITY.html2026-08-02T16:56:52+00:00How to handle temporary SMTP failures correctly with backoff and retries instead of tight retry loops.