SpamHero is an excellent solution for customers at 1&1 (aka 1and1) that want premium spam filtering. 

Here are a few tips to keep in mind when using 1&1 with SpamHero:

• When switching your MX records over to the MX records assigned by SpamHero, the 1&1 control panel warns that all mail services will stop.  The reason this message appears is because 1&1 assumes that by pointing the MX records to an external service, that email will stop delivering to 1&1.  Usually with an MX record change, that is true, but not with SpamHero, since clean email will be delivered to 1&1's servers after it is filtered.
   
• Some 1&1 customers make the mistake of switching the mail delivery host setting in SpamHero so that it sends to the same place as their outbound email server setting in their email software (e.g. smtp.1and1.com).  It is recommended that you keep the mail host delivery set to the default detected by SpamHero (usually starts with mx00... and mx01...).
   
• We did receive feedback from one 1&1 customer that stated that after they switched their MX records to point to SpamHero that the 1&1 control panel stopped allowing them to set up new email addresses.  They got around that issue by temporarily putting the 1&1 MX record back in place.
   
  If you have any other tips to share with other 1&1 customers, please let us know.

Make sure to leave the box unchecked that says "Set 1&1 mail server as backup MX."