While exporting one of the Exchange calendar accounts, DavMail 4.2.1 consistently does not succeed. This may have to do with the sheer size of the account - outputs generate 3 to 6Mb text of ICS markup, and I am not sure this is all of it. The size discrepancy between runs is itself indicative of something being wrong; also, since the markup comes in as chunked-HTTP, I have to parse it into iCS plaintext and have a means to verify validity (via lengths of chunks) - it is often broken, sometimes aborted mid-way, sometimes with an extra byte or two in a chunk.
In fact, more often than not I saw the iCS markup restart in the middle of the file without ending a previous word - beginning again the tags like
PRODID:-//davmail.sf.net/NONSGML DavMail Calendar V1.1//EN
Is there anything I can do to help debug this? Is there any way to request ranges of dates to try decreasing the data size (I only saw constructs like "now - maxage" where maxage is defined in the configs - 90 days by default, several years for me here).
Well, by sheer luck I did get that calendar exported correctly once last night - after tens of automated attempts - the HTTP-unchunking and import to another server both did not complain; the account size was a bit under 4Mb ICS text. Still, this is disturbing… may have to do with stability of the Exchange server which we are trying to ditch here, though.
Anyhow, even if it is causing the resets and restarts mid-connection (making DavMail output a garbage) I'd hope the DavMail layer to detect this and somehow abort the connection or fix the stream (i.e. retry on its own)…