MailFlow v3.5.6
Two provider-behavior fixes, both from reporters who traced their problem precisely enough to make it fixable.
Fixed: providers that limit simultaneous connections (Yahoo)
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Message bodies never loaded on Yahoo accounts (#474), reported and clean-room tested by @amalroymj. Yahoo enforces a small ceiling on simultaneous IMAP sessions per account: the main sync connection worked, and every additional connection MailFlow opened for message bodies, backfill, and folder counts was refused. MailFlow assumed it could open several connections at once and kept trying, which is the same wall Thunderbird once hit with Yahoo.
MailFlow now opens fewer, politer connections to Yahoo: one body connection instead of four, no startup connection burst, background work pauses while the provider is refusing instead of paying one refused login per folder, and no retry ever opens a fresh login during a refusal window. When a message body cannot be fetched because of this, you now get a clear "the mail server is limiting connections, MailFlow is backing off" message instead of a raw server error.
Fixed: a folder could be wrongly emptied from the local cache (Strato)
- Deleting one message made the whole mailbox flash empty (#472), reported by @derolidev with a source-level trace. When the server's answer to "list every message in this folder" came back empty or short for a folder the server had just reported as non-empty, MailFlow trusted the answer and removed every cached message; the next sync restored them, and the cycle repeated every few minutes. Nothing was ever lost on the server; the local cache was wrongly emptied and refilled. MailFlow now refuses to act on a message list that contradicts the server's own message count, the same consistency check its integrity pass has always made. Folders the server reports as genuinely empty still empty normally.
Upgrading
ghcr.io/maathimself/mailflow-backend:latest points at 3.5.6, published for amd64 and arm64.