Messaging posts
Everything in the journal filed under messaging.
2025
The invisible suffix that split every message in two
Two features each appended five characters after the length check ran. Every message crossed a segment boundary and the cost doubled in silence.
Why one Turkish character can double your message cost
Short messages use a 7 bit alphabet with 160 characters, or a 16 bit one with 70. A single accented letter switches the whole message and the bill.
The delivery report that arrives before the record
An asynchronous callback can reach you before the row it refers to is committed. Keep the orphan, retry the match, and stop losing final states.
Treating a rate limit as a permanent failure is expensive
A 429 or a protocol throttle means come back later. A client that files it as a permanent failure throws away paid work and hides the real capacity.
From 300 to 19,000 an hour: where sending throughput actually goes
A sender stuck at 300 messages an hour is not short of CPU or bandwidth. It is waiting for one round trip at a time, and the fix is measurable.
Mail lands in spam: the From alignment nobody checks
SPF and DKIM can both pass while mail keeps landing in spam. The header that explains it names three domains, and DMARC only accepts one answer.