failed: Cached message size smaller than expected

[Hauke Fath]

On Mon, 19 Apr 2021 14:36:07 +0300 (EEST), Aki Tuomi wrote:

[mbox index corruption]

> None of our customers use mbox and there is no mail corruption in 
> mbox. Just dovecot cache is disagreeing with the mail contents, which 
> is automatically healed by removing the cache entry from cache.

We see that a lot here,

read [...] failed: Cached message size smaller than expected (5074 < 
5075, box=INBOX, UID=94)

and it makes for a bad user experience: Clients are hanging while 
attempting to open the mail, and users have to close the window, or 
click on another mail then come back to the first one in order to 
successfully open it. I get a lot of complaints.
 
> I am not sure what's going on with that, hard to say without knowing 
> more about how the system is set up and configured.

There are longstanding problems with Dovecot mbox indexing. I have a 
mail here from 2004 reporting issues. ISTR they went away in late 1.x 
releases (maybe should check with a test install?), then came back with 
2.x.

I've seen index problems reported against maildir and Dovecot's custom 
format. My personal take: If a project cannot fix support of a standard 
format, I am surely not going to follow them into a vendor lock-in.

Would be great if this could be sorted out.

Cheerio,
Hauke

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