Remember the folder's UIDVALIDITY and the last UID read, once the core keeps a sync's state #34

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opened 2026-10-31 03:04:36 +00:00 by tiagoagueda · 0 comments

tiagoagueda commented

2026-10-31 03:04:36 +00:00

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What would change

Remember {folder, uidvalidity, last_uid} in the per-connection state the core issue adds.
At the next pass, if the folder and UIDVALIDITY match, search UID <last_uid+1>:* SINCE <date> and drop any UID not above last_uid from the answer (RFC 3501 6.4.8: n:* always includes the highest UID, even below n). If UIDVALIDITY changed, read the look-back as today.
Record last_uid only for batches read to the end, so a pass cut short resumes where it stopped. The keyword mode is unchanged.
The test double gains UIDVALIDITY/UIDNEXT in its SELECT answer and a UID range in search.
README: lengthening the look-back no longer reaches back for mail already passed over; a changed days resets the state (the core drops it when the configuration is edited).

CONDSTORE/QRESYNC (RFC 7162) is not needed: the plugin never revisits a message.

Accessibility

None.

The whole finding, with its measurements and decisions, is postulo/postulo#1165.

Found by the efficiency and reliability audit of 2026-10-30 (finding PR2; index postulo/postulo#1108). Checked against main at daee30b15 (2026-10-30).

In the modes that do not flag messages (the mailbox left untouched, or a folder that keeps no keywords), every message the rules did not recognise is downloaded again on every pass, within the look-back. ## What would change - Remember `{folder, uidvalidity, last_uid}` in the per-connection state the core issue adds. - At the next pass, if the folder and `UIDVALIDITY` match, search `UID <last_uid+1>:* SINCE <date>` and drop any UID not above `last_uid` from the answer (RFC 3501 6.4.8: `n:*` always includes the highest UID, even below `n`). If `UIDVALIDITY` changed, read the look-back as today. - Record `last_uid` only for batches read to the end, so a pass cut short resumes where it stopped. The keyword mode is unchanged. - The test double gains `UIDVALIDITY`/`UIDNEXT` in its `SELECT` answer and a `UID` range in `search`. - README: lengthening the look-back no longer reaches back for mail already passed over; a changed `days` resets the state (the core drops it when the configuration is edited). CONDSTORE/QRESYNC (RFC 7162) is not needed: the plugin never revisits a message. ## Accessibility None. The whole finding, with its measurements and decisions, is postulo/postulo#1165. --- Found by the efficiency and reliability audit of 2026-10-30 (finding PR2; index postulo/postulo#1108). Checked against `main` at `daee30b15` (2026-10-30).

tiagoagueda added this to the 0.6.0 milestone

2026-10-31 03:04:36 +00:00

tiagoagueda added the

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2026-10-31 03:04:36 +00:00

tiagoagueda referenced this issue from Postulo/postulo

2026-10-31 03:05:04 +00:00

Plugin surface: a sync cannot keep any state between runs, so postulo-imap reads unrecognised mail again on every pass #1165