implement a catchall address for a domain

by specifying a "destination" in an account that is just "@" followed by the
domain, e.g. "@example.org". messages are only delivered to the catchall
address when no regular destination matches (taking the per-domain
catchall-separator and case-sensisitivity into account).

for issue #18

http/account.html

@@ -273,6 +273,7 @@ const index = async () => {
 			Object.entries(destinations).sort().map(t =>
 				dom.li(
 					dom.a(t[0], attr({href: '#destinations/'+t[0]})),
+					t[0].startsWith('@') ? ' (catchall)' : [],
 				),
 			),
 		),

http/admin.go

@@ -1126,8 +1126,8 @@ func (Admin) Domain(ctx context.Context, domain string) dns.Domain {
 	return d
 }
 
-// DomainLocalparts returns the localparts and accounts configured in domain.
-func (Admin) DomainLocalparts(ctx context.Context, domain string) (localpartAccounts map[smtp.Localpart]string) {
+// DomainLocalparts returns the encoded localparts and accounts configured in domain.
+func (Admin) DomainLocalparts(ctx context.Context, domain string) (localpartAccounts map[string]string) {
 	d, err := dns.ParseDomain(domain)
 	xcheckf(ctx, err, "parsing domain")
 	_, ok := mox.Conf.Domain(d)

http/admin.html

@@ -509,6 +509,9 @@ const account = async (name) => {
 							lp, '@',
 							dom.a(d, attr({href: '#domains/'+d})),
 						]
+						if (lp === '') {
+							v.unshift('(catchall) ')
+						}
 					}
 					return dom.tr(
 						dom.td(v),
@@ -568,9 +571,9 @@ const account = async (name) => {
 			fieldset=dom.fieldset(
 				dom.label(
 					style({display: 'inline-block'}),
-					'Email address or localpart',
+					dom.span('Email address or localpart', attr({title: 'If empty, or localpart is empty, a catchall address is configured for the domain.'})),
 					dom.br(),
-					email=dom.input(attr({required: ''})),
+					email=dom.input(),
 				),
 				' ',
 				dom.button('Add address'),
@@ -748,7 +751,7 @@ const domain = async (d) => {
 			dom.tbody(
 				Object.entries(localpartAccounts).map(t =>
 					dom.tr(
-						dom.td(t[0]),
+						dom.td(t[0] || '(catchall)'),
 						dom.td(dom.a(t[1], attr({href: '#accounts/'+t[1]}))),
 						dom.td(
 							dom.button('Remove address', async function click(e) {
@@ -758,7 +761,7 @@ const domain = async (d) => {
 								}
 								e.target.disabled = true
 								try {
-									await api.AddressRemove(t[0] + '@'+d)
+									await api.AddressRemove(t[0] + '@' + d)
 								} catch (err) {
 									console.log({err})
 									window.alert('Error: ' + err.message)
@@ -795,9 +798,9 @@ const domain = async (d) => {
 			fieldset=dom.fieldset(
 				dom.label(
 					style({display: 'inline-block'}),
-					'Localpart',
+					dom.span('Localpart', attr({title: 'An empty localpart is the catchall destination/address for the domain.'})),
 					dom.br(),
-					localpart=dom.input(attr({required: ''})),
+					localpart=dom.input(),
 				),
 				' ',
 				dom.label(

http/adminapi.json

@@ -58,7 +58,7 @@
 		},
 		{
 			"Name": "DomainLocalparts",
-			"Docs": "DomainLocalparts returns the localparts and accounts configured in domain.",
+			"Docs": "DomainLocalparts returns the encoded localparts and accounts configured in domain.",
 			"Params": [
 				{
 					"Name": "domain",
@@ -3237,11 +3237,6 @@
 				}
 			]
 		},
-		{
-			"Name": "Localpart",
-			"Docs": "Localpart is a decoded local part of an email address, before the \"@\".\nFor quoted strings, values do not hold the double quote or escaping backslashes.\nAn empty string can be a valid localpart.",
-			"Values": null
-		},
 		{
 			"Name": "ResultType",
 			"Docs": "ResultType represents a TLS error.",
@@ -3490,6 +3485,11 @@
 				}
 			]
 		},
+		{
+			"Name": "Localpart",
+			"Docs": "Localpart is a decoded local part of an email address, before the \"@\".\nFor quoted strings, values do not hold the double quote or escaping backslashes.\nAn empty string can be a valid localpart.",
+			"Values": null
+		},
 		{
 			"Name": "IP",
 			"Docs": "An IP is a single IP address, a slice of bytes.\nFunctions in this package accept either 4-byte (IPv4)\nor 16-byte (IPv6) slices as input.\n\nNote that in this documentation, referring to an\nIP address as an IPv4 address or an IPv6 address\nis a semantic property of the address, not just the\nlength of the byte slice: a 16-byte slice can still\nbe an IPv4 address.",