I have never had this problem in the 12 years with Comcast until Jan. 2020..all Sent emails disappear immediately after sending. Recipient receives them, but they do not store in my sent folders for even 10 seconds. I checked incoming and outgoing mail server settings and both are accurate.
I logged into my web based comcast email and they are not there either.
I did notice that the sent emails convert to Draft emails with most content missing and the recipient email address and subject line are purged. I work in a field where my sent emails are desperately needed as evidence. I do have virus software installed and download very few apps.
My Inbox is not affected however.
I need these sent emails. Are they retrievable? I am using Android OS.
What email client are you using? I am using Thunderbird and sent myself a test message and the email showed up in the Sent folder on both Thunderbird and webmail. I also checked my Settings in Thunderbird to make sure I had Place a copy in Sent folder was marked.