Definition
STARTTLS
A way to upgrade an SMTP connection from plain text to TLS encryption.
In detail
STARTTLS is a command in SMTP that upgrades the connection to TLS after the initial handshake. Opportunistic TLS means both sides encrypt when they can, but may fall back if negotiation fails (unless you require TLS).
Encrypted hops protect mail in transit between servers that support it. They do not encrypt the message at rest in every mailbox, and intermediate hops vary. Still, requiring TLS to your ESP's submission endpoint is baseline hygiene for credentials and content on that leg.
Reloop's SMTP endpoints expect modern TLS clients for authenticated submission.
In Reloop
How STARTTLS shows up when you use Reloop, hosted or self-hosted.
Related
Nearby terms
Other words that often show up next to STARTTLS.
Ready to reach the inbox?
Built-in SPF/DKIM/DMARC setup, IP warming guidance, and real-time deliverability signals.