Outage in Mailosaur
Some customers unable to forward emails
Resolved MinorIncident Report
We're aware of an issue affecting some customers who are attempting to send emails to external addresses.
As a result of a false-positive inclusion of one of our IP addresses in a blocklist, connections to some mail services are being rejected. The IP in question has since been removed from the list, but it may take several hours for this to propagate to other mail services.
We are continuing to monitor this issue and will update when we're comfortable that this has been fully resolved.
Components affected
Mailosaur SMTP (2525) with STARTTLS Mailosaur SMTP (587) with STARTTLS Mailosaur SMTP (25) Mailosaur SMTP (2525) Mailosaur SMTP (587) Mailosaur SMTP (25) with STARTTLSTrusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
RESOLVED
9 months ago - at 08/11/2025 10:52AM
This incident has been resolved.
MONITORING
9 months ago - at 08/11/2025 10:10AM
We're aware of an issue affecting some customers who are attempting to send emails to external addresses.
As a result of a false-positive inclusion of one of our IP addresses in a blocklist, connections to some mail services are being rejected. The IP in question has since been removed from the list, but it may take several hours for this to propagate to other mail services.
We are continuing to monitor this issue and will update when we're comfortable that this has been fully resolved.
Latest Mailosaur outages
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Intermittent connectivity issues for SMTP and POP3 - about 2 years ago
SMS messages not being delivered to some numbers - over 2 years ago
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