@Jul 24, 2019

There is a bug in the Zoho IMAP server causing all messages to be returned when searching for messages by flag (UNSEEN, FLAGGED, etc), despite specifying a SINCE.

This causes all messages to be synchronized/downloaded, causing a lot of unnecessary traffic for both the user (inconveniently hitting rate limits as well) and for your servers.

See attachment for a protocol log demonstrating this rather serious issue.

The log was captured using imap.zoho.eu


07-24 17:07:32.020 26182 27215 I System.out: BG25 SEARCH OR SINCE 23-Jul-2019 (UNSEEN) ALL
07-24 17:07:32.034 26182 27215 I System.out: * SEARCH 1
07-24 17:07:32.034 26182 27215 I System.out: BG25 OK Success
07-24 17:07:32.035 26182 27214 I System.out: BG26 IDLE
07-24 17:07:32.041 26182 27214 I System.out: + idling
07-24 17:07:32.041 26182 27215 I System.out: DONE
07-24 17:07:32.052 26182 27214 I System.out: BG26 OK IDLE terminated
07-24 17:07:32.053 26182 27215 I System.out: BG27 FETCH 1 (FLAGS UID)
07-24 17:07:32.093 26182 27215 I System.out: * 1 FETCH (FLAGS (\Recent \Seen) UID 3)
07-24 17:07:32.093 26182 27215 I System.out: BG27 OK Success
07-24 17:07:32.093 26182 27214 I System.out: BG28 IDLE
07-24 17:07:32.103 26182 27214 I System.out: + idling
07-24 17:07:32.104 26182 27215 I System.out: DONE
07-24 17:07:32.110 26182 27214 I System.out: BG28 OK IDLE terminated
07-24 17:07:32.110 26182 27215 I System.out: BG29 FETCH 1 (ENVELOPE INTERNALDATE RFC822.SIZE FLAGS BODYSTRUCTURE UID BODY.PEEK[HEADER] RFC822.SIZE INTERNALDATE)
07-24 17:07:32.127 26182 27215 I System.out: * 1 FETCH (FLAGS (\Recent \Seen) INTERNALDATE "08-Jul-2019 23:10:22 +0000" ... redacted

07-24 17:48:15.563 27990 28576 I System.out: * CAPABILITY IMAP4rev1 UNSELECT CHILDREN XLIST NAMESPACE IDLE MOVE ID AUTH=PLAIN SASL-IR UIDPLUS ESEARCH LIST-EXTENDED LIST-STATUS WITHIN LITERAL- APPENDLIMIT=10485760


@Jul 26, 2019

Thank you for contacting Zoho Mail support.

From the records we see that your account ... is not being accessed via IMAP from any IMAP client. Kindly help us with the email address of the Zoho account in which you faced this issue.

We will check with that and assist you further.


@Jul 27, 2019

We have escalated this to our development team. We will check with them and get back to you at the earliest. Please bear with us until then.

Your patience is greatly appreciated!


@Jul 29, 2019

We have checked with our development team and the bug you have reported will be fixed in our upcoming updates. We will keep you notified once we get this fixed. Please bear with us until then.
