Email users report that it takes more than one minute to open emails, including those without attachments. There are three email instances in three different regions hosted by the same CSP. Other…

Since other applications hosted by the same CSP are performing without issues, a general bandwidth problem is less likely, and opening emails without attachments consumes minimal network bandwidth.

While installing monitoring software aids in diagnosis, the question asks for the best solution to *resolve* the issue, and the problem symptom is already clearly identified.

Real-time message scanning by antivirus software often intercepts and processes each email upon access, which introduces significant latency and directly matches the symptom of emails taking an excessive amount of time to open, even if they lack attachments.

Opening emails without attachments generally requires very low IOPS, and if IOPS were a severe global constraint, other applications on the same CSP would likely also experience performance problems.