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Topic: Abnormal upload bandwidth usage

I have iRedmail Pro 4.3 installed on Ubuntu 18.04 installed with the downloadable installer using MySQL on apache. Shortly after replacing my previous mail platform I noticed that my upload bandwidth was abnormal and traced it down to the new mail server. The total mail I have between my 3 domains is 25.48 GB. Typical usage is under 50 sent messages a day and under 200 received. However, my server uploads over 10 gb a day. I'll often see the spike in my traffic log max out my WAN upload speed for up to 20 minutes at a time. I started capturing the traffic and found that the IP addresses receiving the bandwidth match the few offices that download mail from me as well as addresses that belong to mobile networks. I never saw such bandwidth spikes on my previous platform I used and I hosted the same domains and mail. I fail to understand why half the total size of the entire mailboxes would be transmitted every day. Where would I start pinpointing what is using so much data?

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Re: Abnormal upload bandwidth usage

- Does it happen every day? or just the first few days you migrated the server? If just the first few days, it's probably caused due to you didn't migrate the IMAP stats/flags and MUAs consider them as new emails, then download them.
- If you believe it's transferring the mailboxes again and again, you are able to find the login/logout events and the in/out size in Dovecot log files under /var/log/dovecot/*.log.

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Re: Abnormal upload bandwidth usage

Yes this has been every day and I've ignored it but now I need my upload bandwidth back so I need to resolve it. I did see an imap session logout and had a very large amount of data sent out. Not large enough to be the entire mailbox though but definitely larger than the amount of mail they receive daily.

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Re: Abnormal upload bandwidth usage

centaur5 wrote:

I did see an imap session logout and had a very large amount of data sent out. Not large enough to be the entire mailbox though but definitely larger than the amount of mail they receive daily.

Which mail user? Maybe contact him/her to figure out why the account causes a lot traffic?

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Re: Abnormal upload bandwidth usage

I was hoping it would be one offending domain or IP so I could figure out what was going on. However, I'm seeing any IP that is downloading the mail to Thunderbird, outlook, or via their phone is getting the majority of my traffic. When I sort by total traffic used each day it's the IP addresses of their office, home, or ATT Mobile service. The bigger culprits by a huge margin are the IP addresses that are using Thunderbird and outlook.

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Re: Abnormal upload bandwidth usage

centaur5 wrote:

However, my server uploads over 10 gb a day.

Does your server still upload 10GB a day?

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Re: Abnormal upload bandwidth usage

Unfortunately yes. My router shows about 7 or more gigs a day. I rebooted the mail server 5 days ago and since it has been running for 5 days it has uploaded 112.3 gb and downloaded 1.8 gb. I previously used Sogo with Zentyal and didn't have these issues. Not blaming iRedmail as your product is vastly superior to theirs but it's obvious something is wrong. I ignored it but now the upload being capped out is devastating to my network and it needs to stop.

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Re: Abnormal upload bandwidth usage

Try to use tcpdump and check the traffic, it might give you some hint which application is uploading.
I didn't receive similar report from other iRedMail users before, so it's kind of weird to me.

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