The Day Email Left the Building
Outbound mail is invisible until it stops. Quotes not reaching partners, approvals not reaching sites — and every message bouncing back with a stranger's error code.
[contact]Non-delivery reports piling up across the organization. Partners confirm: nothing arriving.
[recon]Traced every bounce to one cause — the sending relay's IP, freshly listed on a Spamhaus blocklist. Every provider honoring the list refused the mail.
[assault]Restored flow immediately with an Exchange Online connection-filter allowlist.
[cleanup]Pursued formal delisting at the source until the relay's reputation came back clean.
[aftermath]Outbound mail restored, relay delisted — sender reputation treated as a production dependency ever since.