A new variant of the Agent Tesla keylogger sends data to special Google GMAIL accounts rather than specific servers.  This malware family has been around since 2014 & attackers continue to evolve & mask capabilities to avoid detection

https://isc.sans.edu/forums/diary/Agent+Tesla+Updates+SMTP+Data+Exfiltration+Technique/28190/

Agent Tesla is a Windows-based keylogger and RAT that commonly uses SMTP or FTP to exfiltrate stolen data.  This malware has been around since 2014, and SMTP is its most common method for data exfiltration. Earlier today, I reviewed post-infection traffic from a recent sample of Agent Tesla.  This activity revealed a change in Agent Tesla’s SMTP data exfiltration technique.

Through November 2021 Agent Tesla samples sent their emails to compromised or possibly fraudulent email accounts on mail servers established through hosting providers.  Since December 2021, Agent Tesla now uses those compromised email accounts to send stolen data to Gmail addresses.