Outage in SMTP2GO
Softbounce Errors
Resolved MajorIncident Report
Summary AI Generated
SMTP2GO's email sending service experienced softbounce errors for approximately 2.4 hours after a patch to their Exim mail server—intended to address SMTP smuggling—altered how the server handled missing carriage return characters (0x0d) before line feeds (0x0a). During the incident, users were advised to connect via specific IP addresses rather than the standard mail.smtp2go.com hostname as a workaround. The issue was resolved within the same day, likely via a rollback of the problematic update.
The team recently updated how our servers process traffic. Specifically, SMTP (https://www.rfc-editor.org/info/rfc5321/#section-2.3.8) requires 0x0d immediately before 0x0a; a recent patch to Exim against "SMTP smuggling" has altered its behavior when it encounters a missing 0x0d.
The team is looking into rolling back this update, but in the meantime, we are suggesting connecting to 45.33.50.34, 43.228.184.6, or 45.33.53.153 instead of the mail.smtp2go.com hostname as a potential workaround.
Components affected
SMTP2GO Email sending (SMTP service)Trusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
RESOLVED
14 days ago - at 10/15/2026 05:23PM
This incident has been resolved.
INVESTIGATING
14 days ago - at 10/15/2026 03:03PM
The team recently updated how our servers process traffic. Specifically, SMTP (https://www.rfc-editor.org/info/rfc5321/#section-2.3.8) requires 0x0d immediately before 0x0a; a recent patch to Exim against "SMTP smuggling" has altered its behavior when it encounters a missing 0x0d.
The team is looking into rolling back this update, but in the meantime, we are suggesting connecting to 45.33.50.34, 43.228.184.6, or 45.33.53.153 instead of the mail.smtp2go.com hostname as a potential workaround.
Latest SMTP2GO outages
Issues with API- statusCode=500 - 22 days ago
Connectivity Issues - 28 days ago
Connection issues and 'processed' emails - 29 days ago
Issues connecting to mail.smtp2go.com - 29 days ago
Email Delivery Delays - AU Region - 30 days ago
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