POP bandwidth sharp increase - please advise

[AdminPWD]

Last month there was a sharp increased use of bandwidth from 14.42MG daily to 2933.73MG daily.
91.83 Meg March in POP to 30.53 Gig in April and five days into May it is already 10.6 Gig, please help me fix this before we end up having to lock the account.

There are only two accounts set up to use POP, they do not use their email on the weekends, and the bandwidth doesn't drop off at all during those days. I switched one of the accounts to IMAP and this also did not lower the bandwidth, it continues to increase.

Security measures that had no effect:
Changed the wordpress site to a new installation of WP and clean theme, new database in a new directory. Changed and strengthened passwords for Cpanel, Wordpress, Email accounts. Contacted my host Site5 and they ran a scan that came back "no malicious files".
The only plugins that I was using was the theme, now I am using Akismet, Wordfence Security - Anti-virus and Firewall security plugin for WordPress.
I also tried activating: DKIM
SPF is disabled
SpamAssassin is now: Enabled (I thought this was already enabled -- I just enabled it though)
Hotlink protection is currently enabled.

If anyone has experienced this issue please let me I'm getting worried!
Thanks all who try to help--

 

[PenguinInternet]

Have you by any chance upgraded to Outlook 2013? We've seen instances of this consuming huge amounts of data transfer for e-mail.

 

[AdminPWD]

Have you by any chance upgraded to Outlook 2013? We've seen instances of this consuming huge amounts of data transfer for e-mail.

Yes one account is running on Outlook 2013 the one converted to IMAP and the other is set up (I'm not sure how since it was configured by the client) using Outlook.com

 

[AdminPWD]

Sorry I just realized that the increase didn't coincide with an Outlook install or upgrade,
they had Outlook configured to look to the GoDaddy webmail server instead of the correct one, since that didn't work the client's email was mainly accessed thru webmail for the one account until they switched to IMAP just a few days ago, IMAP bandwidth went up but POP didn't decrease at all.

 

[PenguinInternet]

We found with a number of our clients that Outlook 2013 was just constantly downloading mail via IMAP and so drastically increasing traffic levels, pushing some over their quota. I'd guess this is the cause of this. Very few of our customers use POP due to it's comparative inflexibility and so I cannot comment on Outlook 2013 with that.

You can always run wireshark and see where the traffic is being used to narrow it down.

 

[rcevans]

We found with a number of our clients that Outlook 2013 was just constantly downloading mail via IMAP and so drastically increasing traffic levels, pushing some over their quota.

Have you (or anyone else) arrived at a solution for Outlook 2013 (IMAP) constantly maxing bandwidth?

I work for a small company (and have somehow assumed the role of de facto IT tech - probably b/c I know how to use google and read cpanel logs) that has exceeded its bandwidth quota for the last 3 billing cycles (which coincides with one of the computers on our server being upgraded to Outlook 2013 IMAP). Based on the bandwidth usage logs, the increased is solely attributable to IMAP activity. We have 4 computers/users using Outlook 10 and one computer/user using Outlook 13, all to connect to 3rd party webmail. I don't have the tools/knowledge to isolate which station is causing the IMAP bandwidth increase. Research has led me to identify Outlook 2013 as the probable culprit, but I have yet to find a solution - and our provider is basically telling us it's our problem to deal with. Any insight and/or assistance would be greatly appreciated.

Note: My office does not use Microsoft Exchange (if that makes any difference). Also, let's assume for purposes of my question that switching to POP is not an option.

Thanks!

 

[cPanelMichael]

Hello

I have seen several reports of issues with Outlook 2013 consuming large amounts of bandwidth. This appears to happen across multiple server environments (cPanel and non-cPanel). You may want to consult directly with the support team for Outlook to see if there is an update on this issue.

Thank you.