5 posts with this tag.
SPF records that trigger more than 10 DNS lookups return permerror and break deliverability. Here's why the limit exists, how to count your lookups, and how to fix it.
MTA-STS lets your domain insist that other mail servers use TLS when delivering to you — closing the longstanding STARTTLS downgrade hole. Here's how it works and how to deploy it.
Every email carries hidden headers that show where it came from, how it travelled, and whether it passed authentication. Here's how to find them and what they mean.
DMARC aggregate (RUA) reports are XML files that look intimidating but tell a simple story. Here's how to read one, what each field means, and what to act on.
SPF softfail (~all) tells receivers an email probably isn't authorised, but to deliver it anyway. Here's what it means, when to use it, and when -all is safer.