fix(sender): add SMTP dial timeouts#1692
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Both tls.Dial (port 465) and smtp.Dial (other ports) could block indefinitely if the remote server is slow to respond, a firewall silently drops packets, or DNS resolution is slow. This caused the entire application to hang on outgoing mail. Replace with tls.DialWithDialer and net.DialTimeout + smtp.NewClient, both using a 30-second timeout. Also switch addr formatting from fmt.Sprintf to net.JoinHostPort for correct IPv6 literal handling.
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This PR exceeds the recommended size of 1000 lines. Please make sure you are NOT addressing multiple issues with one PR. Note this PR might be rejected due to its size. |
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Hi @kawacukennedy! Please fix the following issues with your PR:
- Title: Is too long (49 characters). The PR title must be strictly under 40 characters.
- Body: Missing the
## What?or## Why?headings required by the PR template.
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Benchmark report — no significant changeMetrics worse: 0 · better: 0 (threshold: ±3%). benchstat outputauto-generated by benchmarks.yml |
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Formatting issues have been resolved. Thank you!
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July 20, 2026 09:43
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What?
Add 30-second connection timeouts to both SMTP dial paths (implicit TLS on port 465 and plain TCP for other ports).
Why?
Both
tls.Dialandsmtp.Dialblocked indefinitely if the remote server was slow to respond, a firewall silently dropped packets, or DNS resolution stalled. This hung the entire application with no way to cancel.Also fixed IPv6 address formatting (
fmt.Sprintf→net.JoinHostPort).