I'm having an issue similar to that described in Blank emails to some specific addresses
When I send an e-mail to myself (using SMTP through Civi) it is fine. However, some recipients do not see the body text of e-mails. This occurs with both html and plaintext. It does not appear to be dependent upon the e-mail provider of the recipient, as Gmail (which works for me) does not show the e-mail body for others. One recipient who also has system access sent the test SMTP settings e-mail to themself and it worked, body text included, but sending a regular e-mail through the system did not. I'd greatly appreciate help with this issue as I'm having trouble identifying the cause.
Using 5.3.1, but the issue was present prior to upgrade as well.