и жалобы самому обрабатывать

в смысле насколько эффективно самому хостить систему для рассылок

Мне не для рассылок

А для личной почты

сколько примерно в день шлёшь писем?

Не более 10. В основном принимаю.

тогда можно с чего угодно слать

Но с Digital Ocean меньше всего проблем, тогда получается.

главное читать лог MTA - то есть почтовой программы, которая непосредственно подключается к удалённым MX серверам получателей, и смотреть причины, почему не доставлено.

обычно чтото типа такого пишеться

"Thu Jan 17 2019 14:35:37 GMT+0000 (UTC)","bounced","cmanning@chateaud.com","protocol","reject","501","Syntax error in parameters or arguments","501 Syntax"
"Thu Jan 17 2019 14:30:46 GMT+0000 (UTC)","bounced","anthony.fast@live.com","protocol","reject","501","Email System Sent Bad Command","501 5.5.4 Invalid domain name [AM5EUR02FT010.eop-EUR02.prod.protection.outlook.com]"
"Thu Jan 17 2019 14:26:37 GMT+0000 (UTC)","bounced","yonissiknasty@aim.com","recipient","reject","554","Unknown user","554 delivery error: dd This user doesn't have a aim.com account (yonissiknasty@aim.com) [-9] - mta4053.aol.mail.bf1.yahoo.com"
"Thu Jan 17 2019 14:21:15 GMT+0000 (UTC)","bounced","brettz@dell.com","recipient","reject","550","Mailbox unavailable","550 #5.1.0 Address rejected."
"Thu Jan 17 2019 14:17:39 GMT+0000 (UTC)","bounced","dedmoroz@windfall.ca","recipient","reject","550","Mailbox unavailable","550 Account Inactive"
"Thu Jan 17 2019 14:14:49 GMT+0000 (UTC)","bounced","louis-philippe1988@hotmail.com","protocol","reject","501","Email System Sent Bad Command","501 5.5.4 Invalid domain name [VI1EUR04FT022.eop-eur04.prod.protection.outlook.com]"
"Thu Jan 17 2019 14:14:22 GMT+0000 (UTC)","bounced","ejones1025@bellsouth.com","other","reject","554","Transaction failed","554 Blocked - see https://ipcheck.proofpoint.com/?ip=54.226.20.98"
"Thu Jan 17 2019 14:13:44 GMT+0000 (UTC)","bounced","dilullo@prodigy.net","recipient","reject","553","Unknown Issue With The Receiving System","553 5.3.0 alph151 DNSBL:RBL 521< 54.226.20.98 >_is_blocked.For assistance forward this email to abuse_rbl@abuse-att.net"
"Thu Jan 17 2019 14:13:44 GMT+0000 (UTC)","bounced","xcliu@ca.ibm.com","other","reject","554","Transaction failed","554 Blocked - see https://ipcheck.proofpoint.com/?ip=54.226.20.98"
"Thu Jan 17 2019 14:13:29 GMT+0000 (UTC)","bounced","mdj@educomgov.org","recipient","reject","550","Mailbox unavailable","550 Access denied - Invalid HELO name (See RFC2821 4.1.1.1)"
"Thu Jan 17 2019 14:13:29 GMT+0000 (UTC)","bounced","eddchen@msn.com","protocol","reject","501","Email System Sent Bad Command","501 5.5.4 Invalid domain name [VE1EUR03FT026.eop-EUR03.prod.protection.outlook.com]"
"Thu Jan 17 2019 14:13:28 GMT+0000 (UTC)","bounced","chrisza1@msn.com","protocol","reject","501","Email System Sent Bad Command","501 5.5.4 Invalid domain name [DB5EUR03FT022.eop-EUR03.prod.protection.outlook.com]"
"Thu Jan 17 2019 14:13:21 GMT+0000 (UTC)","bounced","maf005@shsu.edu","protocol","reject","501","Email System Sent Bad Command","501 5.5.4 Invalid domain name [BY2NAM05FT008.eop-nam05.prod.protection.outlook.com]"
"Thu Jan 17 2019 14:13:21 GMT+0000 (UTC)","bounced","jasta@ezlea.com","recipient","reject","550","Mailbox unavailable","550 Access denied - Invalid HELO name (See RFC2821 4.1.1.1)"
"Thu Jan 17 2019 14:13:21 GMT+0000 (UTC)","bounced","juggular.jim289@hotmail.com","protocol","reject","501","Email System Sent Bad Command","501 5.5.4 Invalid domain name [VE1EUR02FT004.eop-EUR02.prod.protection.outlook.com]"
"Thu Jan 17 2019 14:13:20 GMT+0000 (UTC)","bounced","andersondaspida21@hotmail.com","protocol","reject","501","Email System Sent Bad Command","501 5.5.4 Invalid domain name [HE1EUR02FT019.eop-EUR02.prod.protection.outlook.com]"

ну, можно посмотреть что их сервер твоему отвечает

если например ип адреса в чёрных списках, то как говорили, надо менять ип или домены

но обычно на объёмах в 10 писем это маловероятно

А часто проблемы возникают?

если приватьность не шибко принпиципальна, то я бы поизучал https://connect.yandex.ru/

там можно до тысячи адресов бесплатно на своём домене сделать,и приём и отправка.
но если параноить, то можно и у себя на VPS сервак поднять

Домен как-то проблематично просто так взять и поменять

Ведь ради него почта и создаётся

Не, Шмяндексу ни в жизнь

По крайней мере именно шмяндексу