Standard SMTP port, often blocked by ISPs
Alternative to port 25 when blocked
Recommended for email submission
Legacy SSL port, still widely used
Alternative when 587 is blocked
Another alternative port
No encryption (not recommended)
Upgrade to TLS after connection
Modern TLS encryption
Legacy SSL encryption
Basic username/password
Plain text authentication
Challenge-response auth
OAuth 2.0 (Google, Microsoft)
Microsoft Outlook/Office 365
Apple iCloud Mail
AOL Mail
Zoho Mail SMTP
GMX Mail
Mail.com
ProtonMail (Bridge required)
FastMail
Tutanota
Hushmail
Runbox
Mailfence
StartMail
Posteo
Mailbox.org
Disroot
Cock.li
Vivaldi Mail
Kolab Now
Migadu
HEY
La Poste (France)
Orange (France)
SFR (France)
T-Online (Germany)
Seznam.cz (Czech Republic)
Walla! Mail (Israel)
Naver Mail (Korea)
Daum Mail (Korea)
QQ Mail (China)
NetEase 163 (China)
NetEase 126 (China)
Sina Mail (China)
Sohu Mail (China)
Mynet Mail (Turkey)
Yandex Mail (Russia)
Mail.ru (Russia)
Rambler Mail (Russia)
Ukr.net (Ukraine)
Mail.tm (Temporary Email)
Guerrilla Mail
10 Minute Mail
Lycos Mail
Excite Mail
KeeMail
Autistici
Ctemplar (Deprecated)
OpenMailbox (Deprecated)
SendGrid SMTP
Mailgun SMTP
Amazon SES
SparkPost
Mailjet
Mandrill (Mailchimp)
Brevo (SendinBlue)
Postmark
SendPulse
Elastic Email
Pepipost
PolarisMail
MailSnare
Hoster.by (Belarus)
Reg.ru (Russia)
Beget Hosting (Russia)
GoDaddy Hosting
HostGator Hosting
Bluehost Hosting
SiteGround Hosting
Namecheap Private Email
IONOS (1&1) Hosting
DreamHost Hosting
OVH Hosting
Hostinger Hosting
DigitalOcean
Hover
Register.com
Network Solutions
Thexyz
SecureMail.pro
MXroute
CTmail
NeoMailbox
StartLogic
HostPapa
A2 Hosting
InMotion Hosting
GreenGeeks
IceWarp
Kerio Connect
Zimbra
iRedMail
MailEnable
hMailServer
Axigen
Atlassian (Jira/Confluence)
Google Workspace SMTP Relay
Microsoft 365
Gmail SMTP Server
Yahoo Mail SMTP
Custom SMTP Server