fix: typo

feat: improve batv parser and add srs parser

fix: err shadowing

feat(client): extract server name

feat: multiple server addresses, support server address index e.g. ro…

…und robin

feat: smtputf preferred option in vrfy

feat: smtputf8 preferred option

fix: improve data handling

fix: do not allow data or bdat before recipient is set

fix: accept positive smtp status as success in rcpt to and mail from