Hi, just to let you know that when adding the DKIM generated in ISPconfig Email Domain to a TXT record in a DNS zone from your ISP: -It should not have any quotes at the start, at the end and in the middle. -It should not contain spaces -the default name should be: Code: default._domainkey So in your DNS zone it should look like: Code: default._domainkey TXT v=DKIM1;t=s;p=Mwyepiurhkshdfpiuhpkhfpiuehrfihsdkhfpieuht So make sure that in the long string behind p= there are no quotes and no spaces, mine had also spaces. Copy it first to a txt editor like notepad++ and check the string. On my VPS DNS zone it was accepted only without quotes, but according to 2 check sites it was not correct. This site https://dkimcore.org/c/keycheck said, it should not contain quotes. This site https://www.dmarcanalyzer.com said, it should not contain spaces. Now mine came out as This seems to be a valid DKIM Record on both sites. Just to let you know if you have issues with it. Regards!