Some users receive duplicate emails (often 3-5 copies, in one case over 6500 copies arrived). From the DELIVERY LOG it can be seen that the email should be one and not multiple.

Example: this log report 1 e-mail from info@nicolettoc.it to info@plattnersrl.com 

In webmail I see it duplicated 5 times

[2020.01.13] 14:07:04.760 [09561] Delivery started for info@nicolettoc.it at 14:07:04

[2020.01.13] 14:07:10.766 [09561] Added to SpamCheckQueue (1 queued; 1/30 processing)

[2020.01.13] 14:07:10.766 [09561] [SpamCheckQueue] Begin Processin

[2020.01.13] 14:07:11.062 [09561] Starting Spam Checks.

[2020.01.13] 14:07:11.062 [09561] [HoneyPot] Message passed through the honeypot.

[2020.01.13] 14:07:12.484 [09561] Spam check results: [REVERSE DNS LOOKUP: 0,Passed], [NULL SENDER: 0,passed], [_HONEYPOT: 0,passed], [_CYREN: 0,Unknown], [_MESSAGESNIFFER: 0,code:0], [_INTERNALSPAMASSASSIN: 4:7], [_SPF: 0,Pass], [_DKIM: 5,None], [BACKSCATTER: 0,passed], [CBL: 0,passed], [DNS REAL-TIME BLACKHOLE LIST: 0,passed], [HOSTKARMA - BLACKLIST: 0,passed], [HOSTKARMA - BROWNLIST: 0,passed], [MAILSPIKE L3: 0,passed], [MAILSPIKE L4: 0,passed], [MAILSPIKE L5: 0,passed], [MCAFEE: 0,passed], [SEM - BLACK: 0,passed], [SORBS - ABUSE: 0,passed], [SORBS - DYNAMIC IP: 0,passed], [SORBS - NO SERVER: 0,passed], [SORBS - NOMAIL: 0,passed], [SORBS - PROXY: 0,passed], [SORBS - RECENT: 0,passed], [SORBS - SOCKS: 0,passed], [SPAMCOP: 0,passed], [SPAMHAUS - CSS: 0,passed], [SPAMHAUS - PBL: 0,passed], [SPAMHAUS - SBL: 0,passed], [SPAMRATS: 0,passed], [SURRIEL: 0,passed], [TRUNCATE: 0,passed], [UCEPROTECT LEVEL 1: 0,passed], [UCEPROTECT LEVEL 2: 0,passed], [UCEPROTECT LEVEL 3: 0,passed], [SURBL: 0,passed], [SEM-URI: 0,passed], [URIBL BLACK: 0,passed], [URIBL GREY: 0,passed], [URIBL RED: 0,passed]

[2020.01.13] 14:07:12.484 [09561] Spam Checks completed.

[2020.01.13] 14:07:12.484 [09561] Removed from SpamCheckQueue (0 queued or processin

[2020.01.13] 14:07:13.771 [09568] Delivery started for info@nicolettoc.it at 14:07:13

[2020.01.13] 14:07:13.771 [09561] Added to LocalDeliveryQueue (0 queued; 1/50 processing)

[2020.01.13] 14:07:13.771 [09561] [LocalDeliveryQueue] Begin Processing.

[2020.01.13] 14:07:13.771 [09561] Starting local delivery to info@plattnersrl.com

[2020.01.13] 14:07:13.786 [09561] Delivery for info@nicolettoc.it to info@plattnersrl.com has completed (Delivered) Filter: None

[2020.01.13] 14:07:13.786 [09561] End delivery to info@plattnersrl.com (MessageID: <186440366592258577948@AspireOne-PC>)

[2020.01.13] 14:07:13.786 [09561] Removed from LocalDeliveryQueue (0 queued or processing) [2020.01.13] 14:07:16.787 [09561] Removing Spool message: Killed: False, Failed: False, Finished: True

[2020.01.13] 14:07:16.787 [09561] Delivery finished for info@nicolettoc.it at 14:07:16    [id:5609561]