Helldesk Corner: improve imapsync ratio

NethServer Version: 7.9
Module: Email/ IMAP Synchronization

Few days ago i configured imapsync connector for one mailbox with an existing ISP.

After… few attemps of sync i stumbled upon this.
More than 300 messages missing from the local account (born empty). I increased the max message size from 20 to 100mb as a test, no change.

Any hints for reducing delta is appreciated.

Current settings:

For italian reading people: the current ISP is a “famous cheap one” with an island name.

Maybe usage limits are reached?

From Gmail imapsync FAQ:

Q. How many days does it take to transfer X GB?

R. Basically it takes X days to transfer X GB per account.
Gmail has usage limits per day and use throttles when
they are overtaken
Gmail bandwidth limits - Google Workspace Admin Help
From the previous link:

  • Upload with IMAP: 500 MB per day.
    It’s 2X days to upload X GB to Gmail, it’s why I suggest to add
    –maxbytespersecond 20000 --maxbytesafter 1_000_000_000
    for uploading messages to Gmail
    (should be --maxbytespersecond 5787 --maxbytesafter 500_000_000
    but the higher values given work well)
  • Download with IMAP: 2500 MB per day.
    It’s X/2.5 days to download X GB from Gmail, it’s why I suggest to add
    –maxbytespersecond 40_000 --maxbytesafter 3_000_000_000
    for downloading messages from Gmail
    (should be --maxbytespersecond 28_935 --maxbytesafter 2_500_000_000
    That’s empirical values that work in practice.
    Try upper values and see if they still work.
    I would be grateful if you report them to me.

How Gmail says limits are reached?
This is either a disconnection with
“BYE Session expired, please login again”
or a very small rate, less than 1 Kib/s

It’s the max size for one message.


I read somewhere (I think in the official documentation) that even imapsync has its own limit of manageable bandwidth, so much so that it was recommended to start several imapsync processes at the same time in the case of mass migration of mailboxes.

Obviously you can only do it from script, not using the cockpit interface.

Provider is not gmail. And anyway, the gmail account of the issue raised here is not the same of this issue.
And it has… 160mb. Yeah, text and reports don’t eat that space…

Ok. I were wrong. 240mb. Sorry. Google must have a different way of calculate the space occupied…

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