Office process various WordPress based forms as Formidable Pro Plugin which send email receipts. Sometimes, an email receipt can come through corrupted– equal sign along with broken HTML that will appear in the body part of email. However, such happens due to messages received by Outlook clients which is mostly used by everyone for their official purpose.
For more knowledge visit- https://wordpress.org/support/topic/wp-mail-outlook-mime-multipart-issues#post-7670292
MS Outlook is mainly used as an email application. It contain a calendar, task manager, contact manager, note taking, journal and web browsing. All these information is stored in PST file. User can access information from PST file. But sometimes there is problem arises when you want to access data from PST file. The reason behind accessing problem is PST file corruption.