imapsync/FAQ.d/FAQ.Messages_Too_Big.txt
2021-05-01 17:46:04 +02:00

79 lines
No EOL
3.1 KiB
Text

#!/bin/cat
$Id: FAQ.Messages_Too_Big.txt,v 1.4 2020/10/21 09:21:48 gilles Exp gilles $
This document is also available online at
https://imapsync.lamiral.info/FAQ.d/
https://imapsync.lamiral.info/FAQ.d/FAQ.Messages_Too_Big.txt
=======================================================================
Dealing with too big messages with Imapsync.
=======================================================================
Questions answered in this FAQ are:
Q. What does imapsync with big messages?
Q. What can I do to transfer messages bigger than what allows the
imap destination server?
Now the questions again with their answers.
=======================================================================
Q. What does imapsync with big messages?
R. By default, imapsync checks if the host2 imap server announces a
message size limit with "APPENDLIMIT=xxxx" in its CAPABILITY response.
Then imapsync takes this value to set automatically the --maxsize
option, unless --maxsize is already set on the command line
and has a smaller value than the APPENDLIMIT value.
If the host2 imap server doesn't announce any message size
limit then imapsync syncs messages no matter their sizes.
When a message is copied to the destination server, the destination
server accepts it or not but it does it as a whole, it takes the
full message or nothing. Nothing triggers an error in imapsync.
* Gmail announces APPENDLIMIT=35651584 (October 2020).
* Office365 announces nothing.
* Dovecot announces nothing.
=======================================================================
Q. What can I do to transfer messages bigger than what allows the
imap destination server?
R1. A solution is to truncate the message to the maximum size allowed
before copying it to host2. That's a little dirty but it's ok
if you prefer having a truncated message than no message
at all. The attachments after the truncation won't be available
but everything before should be ok. It may also depends
on the software tool reading the email message.
For example,
Gmail currently limits messages to 35651584 bytes (October 2020),
Starting with imapsync release 1.938 option --truncmess xxxx truncates
messages bigger than the given size xxxx.
imapsync --truncmess 35651584 --appendlimit 1000000000000
Prior to imapsync release 1.938, instead of --truncmess:
On Linux, use:
imapsync ... --pipemess 'perl -0ne "print substr \$_,0,35651584" '
On windows, use:
I'm not sure of (not tested yet):
imapsync ... --pipemess "perl -0ne 'print substr $_,0,35651584' "
R2. A not so dirty solution would be to transform the message and
include links to the big attachments, instead of the attachments.
Well, not done yet and too much complicted compared to the simple
solution which is to allow big messages on the destination account.
=======================================================================
=======================================================================