We will change to a new server on aws soon. The address points to the old server. Still, we already get "visits" from various "hackers". Attaches a small excerpt from the SMTP log. Is there any way to block these? Any other ideas?

00:10:03 [167.71.213.231][51934436] rsp: 220 mail.xxxxxx.com

00:10:03 [167.71.213.231][51934436] connected at 2/24/2022 12:10:03 AM

00:10:03 [167.71.213.231][7889396] rsp: 220 mail.xxxxxx.com

00:10:03 [167.71.213.231][7889396] connected at 2/24/2022 12:10:03 AM

00:10:04 [167.71.213.231][7889396] cmd: helo ec2-xx-xx-xxx-xxx.eu-north-1.compute.amazonaws.com

00:10:04 [167.71.213.231][7889396] rsp: 250 mail.xxxxxx.com Hello [167.71.213.231]

00:10:04 [167.71.213.231][7889396] cmd: mail from: <it@ec2-xx-xx-xxx-xxx.eu-north-1.compute.amazonaws.com>

00:10:04 [167.71.213.231][7889396] rsp: 550 This is a submission only port. You must authenticate before sending mail

00:10:04 [167.71.213.231][7889396] cmd: rcpt to: <it@vdeassetmanagement.co.uk>

00:10:04 [167.71.213.231][7889396] rsp: 503 Bad sequence of commands

00:10:05 [167.71.213.231][7889396] cmd: quit

00:10:05 [167.71.213.231][7889396] rsp: 221 Service closing transmission channel

00:10:05 [167.71.213.231][7889396] disconnected at 2/24/2022 12:10:05 AM

00:10:05 [167.71.213.231][51934436] disconnected at 2/24/2022 12:10:05 AM

01:20:27 [50.116.61.171][12755849] rsp: 220 mail.xxxxxx.com

01:20:27 [50.116.61.171][12755849] connected at 2/24/2022 1:20:27 AM

01:20:27 [50.116.61.171][12755849] cmd: EHLO masscan

01:20:27 [50.116.61.171][12755849] rsp: 250-mail.xxxxxx.com Hello [50.116.61.171]250-SIZE 31457280250-AUTH LOGIN CRAM-MD5250-STARTTLS250-8BITMIME250 OK

01:20:27 [50.116.61.171][12755849] cmd: STARTTLS

01:20:27 [50.116.61.171][12755849] rsp: 220 Start TLS negotiation

01:20:28 Exception [Authentication failed because the remote party has closed the transport stream.]

01:20:28 [50.116.61.171][12755849] disconnected at 2/24/2022 1:20:28 AM

02:16:12 [88.68.44.80][21599033] rsp: 220 mail.xxxxxx.com

02:16:12 [88.68.44.80][21599033] connected at 2/24/2022 2:16:12 AM

02:16:12 [88.68.44.80][21599033] cmd: EHLO unread.dyndns.info

02:16:12 [88.68.44.80][21599033] rsp: 250-mail.xxxxxx.com Hello [88.68.44.80]250-SIZE 31457280250-AUTH LOGIN CRAM-MD5250-STARTTLS250-8BITMIME250 OK

02:16:12 [88.68.44.80][21599033] cmd: HELP

02:16:12 [88.68.44.80][21599033] rsp: 502 Command not implemented

02:16:12 [88.68.44.80][21599033] cmd: QUIT

02:16:12 [88.68.44.80][21599033] rsp: 221 Service closing transmission channel

02:16:12 [88.68.44.80][21599033] disconnected at 2/24/2022 2:16:12 AM