Some of the DNS hosting servers do add the domain value automatically at the end of the hostname.


For example, if you wanted to add a CNAME value as following:


TYPEHOSTVALUE
CNAME
mmemail.massmailer.io
u14107014.wl015.sendgrid.net


Depending on how your DNS server hosting behaves you may or may not need to add the 'massmailer.io' for the HOST.


If your DNS host adds the domain automatically at the end of the HOST then you will just have to add as follows:



TYPEHOSTVALUE
CNAME
mmemail
u14107014.wl015.sendgrid.net


Some DNS hosts may want you to add period, "." at the end as shown in the table below:



TYPEHOSTVALUE
CNAME
mmemail.massmailer.io.
u14107014.wl015.sendgrid.net.


OR


TYPEHOSTVALUE
CNAME
mmemail
u14107014.wl015.sendgrid.net.


So, we recommend that you work with your DNS host support team to make sure that the values have been added properly.


You can check the DNS values if they are added properly or not at https://mxtoolbox.com/NetworkTools.aspx


Following is an example setting on hostlabs.com