Resolved Email arrives but only on webmail

[Carloz]

Hello, one of my customers says that when his customers send e-mails to him (for example 2 e-mails), the first arrives, and the second don't. So, to see the second e-mail, he must use the webmail (horde). On the webmail he sees all the e-mails (but the second e-mail, that he doesn't see on the mail client, is always strikethrough).

He usually uses "mail" (apple client mail software). He just tryed to uses mozilla thunderbird as a mail client, to understand if the issue is related to "mail" apple software, and he found that the issue occurs also with Thunderbird.

Any ideas on how to solve this problem or to understand exactly what it is about?

The plesk version is:
Plesk Onyx
Versione 17.5.3 Aggiorna #19, ultimo aggiornamento il 26/Ago/2017 10.05

Thanks,

Carlo

 

[Carloz]

Hello, my coustomer still have the problem, and now also some single e-mails don't arrive. I checked the mailbox size, and it's busy for 1,9 Gigabytes of 5 Gigabytes total, so the mailbox is not full. Can you please reply to me? Is there a method to check e-mails that doesn't arrive and the reasons why they don't arrive? (For example analyzing some debug logs, etc):

The issue is very serious and it is causing many discomforts to my customer, so please reply asap. Thanks.

 

[Suman]

Just talk to your hosting provider.There must be some issue with your webmail setting. They will definitely solve this. I was also getting the similar type of error. Mine incoming was working fine. Just outgoing mails are blocked. They solved them my issue. Now, the things are working fine.