Update domains.csv: add fastmail.com

autoconf/domains.csv

@@ -55,6 +55,7 @@ email.arizona.edu,mail.catnet.arizona.edu,993,smtpgate.email.arizona.edu,587
 email.com,imap.mail.com,995,smtp.mail.com,587
 engineer.com,imap.mail.com,995,smtp.mail.com,587
 europe.com,imap.mail.com,995,smtp.mail.com,587
+fastmail.com,imap.fastmail.com,993,smtp.fastmail.com,465
 firemail.cc,mail.cock.li,993,mail.cock.li,587
 getbackinthe.kitchen,mail.cock.li,993,mail.cock.li,587
 gmail.com,imap.google.com,993,smtp.gmail.com,587